DJS 87:2017 ICS 67.220.20

Draft

Jamaican Standard

Specification

for

Fluoridated iodized salt - food grade salt

BUREAU OF STANDARDS JAMAICA

COMMENT DEADLINE: 17 MAY 2017- 15 JULY 2017

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Kingston 10 Jamaica W.I.

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JS 87:201X

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JS 87:2017 D

JBS CERTIFICATION MARK PROGRAMME

The general policies of the JBS Certification Mark Programme are as follows: - The JBS provides certification services for manufacturers participating in the programme and licensed to use the gazetted JBS Certification Marks to indicate conformity with Jamaican Standards.

- Where feasible, programmes will be developed to meet special requirements of the

submitter. Where applicable, certification may form the basis for acceptance by inspection authorities responsible for enforcement of regulations.

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CERTIFICATION MARKS

Product Certification Marks Plant Certification Mark

Certification of Agricultural Produce Jamaica-Made Mark (CAP) Mark

JS 87:2017 D

Draft

Jamaican Standard

Specification

for

Fluoridated iodized salt -food grade salt

Bureau of Standards Jamaica

6 Winchester Road

P.O. Box 113

Kingston 10

JAMAICA W.I.

Tel: 876-926-3140/618 - 1534

Fax: 876-929-4736

E-mail: info@bsj.org.jm

Month 201X

DJS 87:2017

ii

© 201X Bureau of Standards Jamaica

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or

by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the

Bureau of Standards Jamaica.

ISBN

Declared by the Bureau of Standards Jamaica to be a standard specification pursuant to section 7 of the Standards Act 1969.

First published August 1985

Second edition November 2008

This standard specification was circulated in draft form for comment under the reference DJS 87:2017

Jamaican Standards establish requirements in relation to commodities, processes and practices, but do not purport to include all

the necessary provisions of a contract.

The attention of those using this standard specification is called to the necessity of complying with any relevant legislation.

Amendments

No.

Date of

issue

Remarks

Entered by

and date

3

DJS 87:2017

Contents

Page

Foreword iv

Committee representation iv

Acknowledgment iv

Related documents iv

Specification

1 Scope 1

2 Product description 1

3 General requirements 1

4 Detailed requirements 1

5 Packaging 2

6 Labelling 2

7 Sampling 3

8 Safety precautions and disposal of waste

Appendices

A Determination of chloride in salt 4

B Determination of moisture in salt 5

C Determination of iodide (Selective ion electrode) and iodate in salt 6

D Determination of fluoride-Selective ion electrode 9

E Methods for determination of anti-caking additives content of salt for food use 11

F Determination of iron in salt 15

G Determination of sulphate, calcium and magnesium in salt 16

H Determination of matter insoluble in water or in acid and preparation of principal

solutions for other determinations 18

J Determination of arsenic-Silver diethyl dithio-carbamate red complex absorptiometric

method 20

K Method for the determination of copper in sodium chloride 23

L Method for the determination of lead in sodium chloride 26

M Method for the determination of mercury in sodium chloride 31

N Method for the determination of cadmium in sodium chloride 36

P Sampling plan for salt 41

Q Volumetric conversion table (as they occur in sequence) 42

Tables

1 Mass of potassium hexacyanoferrate in standard solutions 12

2 Statistical results of comparative analysis 19

3 Mass of copper in standard solutions 24

4 Mass of lead in standard solution 28

5 Mass of mercury in standard solutions 34

6 Mass of cadmium in standard solution 38

7 Sampling size 41

Figures

1 Apparatus for arsenic determination 21

2 Typical apparatus for determination of mercury by atomic absorption

spectrometry 34

4

DJS 87:2017

Foreword

This standard is a revision of and replaces JS 87:1985 Jamaican Standard Specification for salt.

JS 87:1985 was revised to include fluoride and its test method and to update other test methods. The name has been changed

to reflect the addition of fluoride and the previous inclusion of iodide; and with special emphasis on the classification of the salt as ‘food grade salt’.

The Ministry of Health has established that fluoride intake in the human body reduces the incidences of cavities especially in

children. The Ministry will therefore put regulations in place to ensure that salt used for household and food processing be

fluoridated. This means that any such salt, whether manufactured in or imported into Jamaica, must meet the requirements of

this standard. This resulted in a request to the Bureau of Standards Jamaica (hereinafter referred to as the “Bureau”) for JS

87:1985 to be revised to include fluoride and its test method.

The revised standard will therefore be referenced in regulations under the Ministry of Health’s Acts therefore designating it

as a technical regulation with mandatory implications.

The standard is intended to be mandatory.

Committee representation

The revision of this standard for the Standards Council, established by the Standards Act 1969 was carried out under the

supervision of the Bureau’s National Food Standards Technical Committee which at the time comprised the following members:

Acknowledgement

Acknowledgment is made to the following institutions for permission to reproduce material from the following documents:

British Standards Institution BS 998 Bureau of Indian Standards IS 253 Bureau of Indian Standards IS 2860 International Organization for Standardization ISO 2859

Tanzania Bureau of Standards TZS 132

Official Methods of Analysis of the Association of Official Analytical Chemists, 18th edition, 2005

Vogel’s Textbook of Quantitative Chemical Analysis (Fifth edition) A-1 Vogel.

Related documents

This standard makes reference to the following:

BS 998 Specification for vacuum salt for food use

IS 253 Edible common salt IS 2860 Methods of sampling and test for processed fruits and vegetables

ISO 2859 Sampling procedures and tables for inspection by attributes

JS 36 Jamaican Standard Specification for Processed foods (general)

JS 1 Part: 20 Jamaican Standard Specification for Labelling of commodities Part 20: Labelling of prepackaged goods

Official Methods of Analysis of the Association of Official Analytical Chemists, 18th edition, 2005

Orion Ionplus Fluoride Electrode Instruction Manual, Thermo Electron Corporation Website, www.thermo.com

Orion Ionplus Iodide Electrode Instruction Manual, Thermo Electron Corporation

Quality Manual of the Industrial Chemical Company Limited

TZS 132:1981 Edible Common Salt Specification

Vogel’s Textbook of Quantitative Chemical Analysis, Fifth Edition

1

DJS 87:2017

Draft Jamaican Standard Specification for Fluoridated iodized salt - food grade salt

1. Scope

This standard prescribes requirements for fluoridated iodized salt, which is intended for human

consumption as well as for food processing. Salt, which is a by-product of the fertilizer or chemical

industries, is not covered by this standard.

2.Product

description

The product shall be white crystalline sodium chloride free from visible impurities and shall be either

rock salt, sea salt or vacuum evaporated salt, which has been fluoridated and iodized.

3. General

requirements

The product shall comply with the requirements of JS 36.

4. Detailed

requirements

4.1 Sodium chloride. The product shall not contain less than 98% by weight of sodium chloride when

tested by the method described in appendix A.

4.2 Moisture. The dried product shall contain no more than 0.5% by weight of moisture when tested

by the method stipulated in appendix B. The moisture content of un-dried salt shall not be greater than

4% by weight.

4.3 Additives. All additives used shall be of food grade quality.

4.3.1 'Free flowing' or 'free running' salt shall contain an approved anti-caking agent.

4.3.2 Salt labelled 'iodized' shall contain not less than 0.006% and not more than 0.01% by weight of

potassium or sodium iodide or iodate together with a suitable stabilizer when tested as directed in

appendix C.

4.3.3 The level of fluoride should be within 200 mg/kg to 250 mg/kg (see appendix D).

4.3.4 Not more than 13 ppm of potassium hexacyanoferrate II (Ferro cyanide) [or hexacyanoferrate

(Ferro cyanide) II salts of sodium, calcium and manganese] shall be present when tested in accordance

with the requirements of appendix E.

4.4 Purity. The limits of impurities, when determined by the methods described in appendices F to N

shall be as follows:

(a) Not more than 10 ppm of iron shall be present (see appendix F).

(b) The sulphate content shall not exceed 0.5% (see appendix G).

(c) The calcium and magnesium content shall not exceed 0.2% by weight of each ion

(see appendix G)

(d) Matter insoluble in water shall not exceed 0.3% (see appendix H).

(e) Not more than 0.5 ppm of arsenic shall be present (see appendix J).

(f) Not more than 2 ppm of copper shall be present (see appendix K).

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DJS 87:2017

(g) Not more than 2 ppm of lead shall be present (see appendix L)

3

DJS 87:2017

(h) Not more than 0.1 ppm of mercury shall be present (see appendix M).

(i) Not more than 0.5 ppm of cadmium shall be present (see appendix N).

4.5 Particle size

4.5.1 Re-crystallized table salt and solar evaporated salt. Not less than 95% shall pass through a U.S.

Standard No. 30 (600 µ ) sieve and less than 10% shall pass through a U.S. Standard No. 100 (150 µ )

sieve.

4.5.2 Special products. The particle size is subject to agreement between manufacturer and purchaser.

5. Packaging

5.1 Only packaging materials which are not likely to impair the organoleptic or chemical

characteristics of salt or make them harmful to health may be used. The materials used for packaging

should be mutually compatible with salt.

5.2 Only packaging materials which are approved by the Bureau shall be used.

6. Labelling

The information on the labels shall comply with the requirements of the Jamaican Standard

Specification for the Labelling of commodities Part 20: Labelling of prepackaged goods (JS 1 Part:

20), as well as with the following, where not detailed in JS 1 Part: 20:

(a) product name;

(b) name and address of manufacturer, distributor or importer;

(c) country of origin;

(d) net quantity declaration;

(e) date mark;

(f) batch code;

(g) ingredients listing;

(h) additives;

(j) list of impurities;

(k) brand name, if any;

(l) storage instructions;

(m) precautionary statement;

(n) instructions for use.

7. Sampling

The salt shall be sampled in accordance with appendix P.

4

DJS 87:2017

8. Safety precautions and disposal of waste

All chemicals must be used according to appropriate safety precautions. All waste generated shall be

discarded in an environmentally friendly manner.

5

DJS 87:2017

Appendix A

Determination of chloride in

salt

A.l Reagents

(a) Concentrated nitric acid (HNO3).

(b) Silver nitrate solution (AgNO3) 0.1 M (0.1 N).

(c) Diluted nitric acid (0.5 mL HNO3 to 200 mL H2O).

(d) Hydrochloric acid (HCl) 0.l M (0.1 N).

A.2 Procedure

Weigh accurately 0.2 g of sample into a 400 mL beaker. Add 150 mL water and stir until the solid is

dissolved. Add 0.5 mL concentrated HNO3. Cool and add 0.1 M (0.1 N) AgNO3 slowly with constant

stirring. Only a slight excess of 0.1 M (0.1 N) AgNO3 should be added. This is detected by allowing

the precipitate to settle and adding a few drops of AgNO3 until no further precipitation occurs. The

determination should be carried out in subdued light.

Heat the suspension nearly to boiling point while stirring constantly and maintain it at this temperature

until the precipitate coagulates and the supernatant is clear. Ensure that precipitation is complete by

adding AgNO3 solution to the supernatant. Allow the solution to stand in the dark for 1 h after

precipitation is complete.

Wash the precipitate two or three times by decantation with 10 mL of cold dilute HNO3 before

transferring the precipitate to a previously dried and weighed sintered glass crucible. Transfer the

precipitate using a 'policeman' and wash the precipitate with dilute HNO3 until 5 mL portions of the

washing gives no turbidity with one or two drops of 0.l M (0.l N) HCl. Dry the crucible and contents

at 140°C (284°F) in an air oven to constant weight.

A.3 Calculation

% Chloride = 0.2474 × weight of residue × 100

weight of sample used

% Sodium Chloride = 0.4077 × weight of residue × 100

weight of sample used

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DJS 87:2017

Appendix B

Determination of moisture in salt

B.1 Procedure

Place 10g sample in a previously dried and weighed silica dish. Spread sample evenly over the bottom

of the dish. Heat for 1 h periods at 140°C until 2 consecutive weighings agree within 5mg.

B.2 Calculation

% moisture (dry basis) =

weight loss × 100

weight of dry sample

DJS 87:2017

6

Appendix C

Determination of iodide (Selective ion electrode) and iodate in salt

C.1 Iodide determination

C.1.1 Reagents

(a) De-ionized water of high quality must be used for the preparation of all solutions.

(b) Commercially available iodide standard of 0.10 M. Dilute 78.7 mL of 0.10 M iodide standard

and make up to 1 L in a volumetric flask. This yields a 1000 ppm iodide stock solution which

should be prepared fresh weekly and stored in plastic bottles.

(c) Commercially available electrode filling solution. Optimum Results D for Orion 96-53

Combination Iodide Electrode.

(d) Commercially available Ionic Strength Adjustor (ISA).

C.1.2 Apparatus

(a) pH/mV meter with minimum resolution of 0.1 mV.

(b) Combination Iodide Electrode (Orion 96-53).

(c) Magnetic stirrer and teflon coated stir bars.

(d) Plastic beakers.

C.1.3 Procedure

C.1.3.1 Preparation of calibration curve

(a) Dilute the stock 1000 ppm iodide standard to prepare a series of standards with target

concentrations of 1 ppm, 5 ppm, 10 ppm, 20 ppm, and 100 ppm.

(b) Mix in a plastic beaker with the aid of the stirrer, 100 mL of the 1 ppm standard and 2 mL of ISA.

(c) Rinse the electrode, blot dry and obtain milli-volt reading as described by the meter manufacturer.

(d) Rinse electrode, blot dry and repeat for the remaining standards in increasing order of

concentration.

(e) Plot a graph of milli-volt reading against log [I -], where [I

-] represents concentration of iodide (ppm)

in iodide standard.

(f) Use linear regression analysis to obtain the best fit line of form.

E = Eo + S Log[I − ]

DJS 87:2017

7

where:

E is the measured potential, mV;

Eo is the intercept determined from the graph, mV; S is the slope determined from the graph, mV.

(Remember the x axis is a log scale and will range from 0 to 2)

C.1.3.2 Sample preparation and analysis. With the aid of the stirrer, dissolve 50.0 ± 0.1g of salt sample

in de-ionized water and make up to 250 mL in a volumetric flask.

Mix 100 mL of the solution with 2 mL TISAB II and measure the potential (Es) similar to standards.

Using this value, re-arrange the equation in C.1.3.1 and determine the [I-] in ppm of the solution.

( Es − Eo \

I I

[I −

] = 10 S

Multiply the iodide concentration of the solution by 5.0 to get the iodide content of the solid in mg iodide

per kg solid salt.

C.2 Iodate determination

C.2.1 Reagents

(a) (1M) sulphuric acid.

(b) 0.001 M sodium thiosulphate.

(c) Starch solution.

(d) Potassium iodide (iodate-free).

C.2.2 Procedure

(a) Weigh 25 g salt and make up to 100 mL in a 250 mL conical flask with de-ionized water.

(b) Add 2 g of potassium iodide (iodate-free) and 5 mL (1M) sulphuric acid.

(c) Titrate the liberated iodine with 0.001 M sodium thiosulphate.

(d) When the colour of the solution becomes slightly yellow, add 2 mL of starch solution and continue

the titration until colour moves from dark blue to colourless.

where:

IO3 + 5 I

- + 6 H

+ --- 3 I2 + 3 H2O

2 S2O32-

+ I2 --- S4O6 2-

+ 2 I-

DJS 87:2017

8

C.2.3 Calculations

Concentration of iodate in ppm =

Volume of thiosulfate (mL) × concentration of thiosulfate (M ) × 175 × 1000

150

DJS 87:2017

9

Appendix D

Determination of fluoride – Selective ion electrode

D.1. Reagents

(a) De-ionized water of high quality must be used for the preparation of all solutions.

(b) Commercially available fluoride standard – 100 ppm.

Alternatively, dissolve 0.221 g analytical grade anhydrous sodium fluoride (NaF) in de-ionized water and dilute to 1.0 L. This must be stored in an air-tight plastic container (glassware tend to absorb fluoride

ions).

(c) Commercially available electrode filling solution – Optimum Results A for Orion 96-09 Combination

electrode.

(d) Commercially available Total Ionic Strength Adjustor Buffer (TISAB II)

D.2. Apparatus

(a) pH/mV meter with minimum resolution of 0.1 mV.

(b) Combination Fluoride electrode (Orion 96-09).

(c) Magnetic stirrer and teflon coated stir bars.

(d) Plastic beakers.

D.3. Procedure

D.3.1. Preparation of calibration curve

(a) Dilute the stock 100 ppm fluoride standard to prepare a series of standards with target concentrations

of 1 ppm, 5 ppm, 10 ppm, 20 ppm, and 100 ppm.

(b) Mix in a plastic beaker with the aid of the stirrer, 50 mL of the 1 ppm standard and 50 mL of

TISAB II.

(c) Rinse the electrode, blot dry and obtain milli-volt reading as described by the meter manufacturer.

(d) Rinse electrode, blot dry and repeat for the remaining standards in increasing order of

concentration.

(e) Plot a graph of milli-volt reading against log [F -] where [F

-] represents concentration of fluoride

(ppm) in standard.

(f) Use linear regression analysis to obtain the best fit line of form.

E = Eo + S Log[F − ]

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DJS 87:2017

where:

E is the measured potential, mV

E o is the intercept determined from the graph, mV S is

the slope determined from the graph, mV (Remember the x axis is a log scale and will go from 0 to 2)

D.3.2. Sample preparation and analysis. With the aid of the stirrer, dissolve 50.0 ± 0.1g of salt sample in

de-ionized water and make up to 250 mL in a volumetric flask. Sample from C.1.3.2 can be used. Mix 50

mL of the solution with 50 mL TISAB II and measure the potential (Es) similar to standards. Using this

value, re-arrange the above equation and determine the [F -] in ppm of the solution.

( Es − Eo \

[F −

I I

] = 10 S

Multiply the fluoride concentration of the solution by 5.0 to get the fluoride content of the solid in mg

fluoride per kg solid salt. Detection limit is about 0.02 mg/L fluoride.

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DJS 87:2017

Appendix E

Methods for the determination of anti-caking additives content of salt for food use

E.1 Methods.

There are two methods for the determination of water-soluble hexacyanoferrate (II) (anti-caking

additives) in salt for food use. The two methods are applicable to products having levels of

hexacyanoferrate (II), as follows:

(a) direct method - for 2.5 mg to 4 mg of hexacyanoferrate (II) per kg of salt.

(b) filtration method - for 0.25 mg to 4 mg of hexacyanoferrate (II) per kg of salt.

E.2 Principle

(a) Hexacyanoferrate (II) with iron (II), in acid solution, forms the complex iron (II) hexacyanoferrate (II)

which, in the presence of iron (III), oxidizes immediately to Prussian blue. The absorbance of this

complex is determined at the wavelength of maximum absorbance (approximately 700 nm).

(b) For the lower levels of potassium hexacyanoferrate (II) the Prussian blue is filtered on a membrane

filter. After re-dissolving it in potassium hydroxide solution, the Prussian blue is reformed in a much

reduced volume.

NOTE 1. Hexacyanoferrate (III) is determined simultaneously. NOTE 2. The intensity of the colour depends on the amount of alkali metal ions present in the solution.

E.3 Reagents

General. Use only reagents of recognized analytical grade and water complying with grade 3 of BS EN

ISO 3696.

(a) Sulphuric acid, standard volumetric solution, c (½H2SO4) 1.0 mol/L exactly.

(b) Potassium hydroxide, standard volumetric solution, c (KOH) 0.05 mol/L exactly.

(c) Sodium chloride, hexacyanoferrate-free.

(d) Iron (II)/Iron (III) solution. Dissolve in water, in a 1 L one-mark volumetric flask, 200 g of ammonium iron (II) sulphate hexahydrate, (NH4)2SO4.FeSO4.6H2O, and 25 g of hydrated ammonium iron

(III) sulphate, (NH4)2SO4.Fe2(SO4)3.24H2O. Add 100 mL of the sulphuric acid solution [see E.3 (a)].

Dilute with water to the mark and mix well. Filter the solution and store in a dark bottle.

(e) Potassium hexacyanoferrate (II) stock solution, containing 1 mg/mL of potassium hexacyanoferrate. Dissolve in water, in a 1 L one-mark volumetric flask 1.000 g of potassium hexacyanoferrate (II)

trihydrate, K4Fe(CN)6.3H2O. Add 5 mL of the potassium hydroxide solution [see E.3 (b)]. Dilute with

water to the mark and mix well. Store this stock solution in a dark bottle for a maximum of 1 month.

(f) Potassium hexacyanoferrate (II) standard solution, containing 50 µ g/mL of K4Fe (CN)6.3H2O. Take

50.0 mL of the stock solution [see E.3 (e)] and transfer to a 1 L one-mark volumetric flask. Add 5 mL of

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DJS 87:2017

the potassium hydroxide solution [E.3 (b)]. Dilute with water to the mark and mix well. Prepare this

solution at the time of use.

E.4 Apparatus

(a) Ordinary laboratory apparatus.

(b) Spectrometer or photometer, fitted with filters having a maximum transmission between 690 nm and

710 nm.

(c) Membrane filter of approximately 50 mm diameter and pore size maximum of 0.3 µ m.

E.5 Procedure

E.5.1 Test portion. Weigh, to the nearest 0.1 g a test portion of approximately 100 g.

E.5.2 Blank test. At the same time as the determination carry out a blank test, following the same

procedure and using the same quantities of reagents and the same quantity of the sodium chloride

[E.3(c)], but omitting the test portion.

E.5.3 Preparation of the calibration curve

E.5.3.1 Preparation of standard colorimetric solutions. Into a series of five 100 mL one-mark volumetric

flasks, introduce 10.0 g of the sodium chloride [E.3(c)] and the volumes of the potassium

hexacyanoferrate (II) solution [E.3 (f)] as shown in table 1. Dilute the solutions to approximately 50 mL

with water, swirl until the crystals are dissolved and then add 10.0 mL of the potassium hydroxide

solution [E.3 (b)].

Table 1. Mass of potassium hexacyanoferrate in standard solutions

Volume of standard solution [E.3(f)]

/ mL

Corresponding mass of K4Fe(CN)6.3H2O /µ g

0 *

2

5

10

15

0

100

250

500

750

* zero standard

Add, in the order given, 5 mL of the sulphuric acid solution [E.3 (a)] and 5 mL of the iron (II)/iron (III)

solution [E.3 (d)]. Mix the solution after each addition. Dilute with water to the mark and mix well.

E.5.3.2 Photometric measurements. Adjust the apparatus to zero absorbance with respect to water prior to

each measurement. Measure the absorbance of each solution, using either the spectrometer at the

wavelength of maximum absorbance (approximately 700 nm) or the photometer [E.4 (a)], fitted with the

filters specified. Deduct the absorbance of the zero standard from the absorbance obtained for each

standard colorimetric solution (see E.5.3.1).

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DJS 87:2017

E.5.3.3 Plotting the calibration curve. Plot a graph having, for example, the masses of K4Fe (CN)6.3H2O

contained in 100 mL of the standard colorimetric solutions (see E.5.3.1), expressed in micrograms, as abscissae, and the corresponding values of absorbance as ordinates. Prepare a new calibration curve whenever a new stock solution (E.3(e)] is prepared.

E.5.4 Determination

E.5.4.1 Preparation of the test solution

E.5.4.1.1 Direct method [see E.1 (a)] Add the test portion (see E.5.1) to a 500 mL one-mark volumetric

flask. Dissolve in water, dilute with water to the mark and mix well. Take 50.0 mL of this solution and

place in a 100 mL one-mark volumetric flask. Add 10 mL of the potassium hydroxide solution [E.3 (b)].

Follow the procedure described in E.5.4.2.

E.5.4.1.2 Filtration method. Transfer the test portion (see E.5.1) to a 600 mL beaker, dissolve in 450 mL

of water and add 10 mL of the sulphuric acid solution [E.3 (a)] and 25 mL of the iron (II)/iron (III)

solution [E.3 (d)]. Mix the solution after each addition. Allow it to stand for 15 min. Filter the precipitate

under vacuum on the membrane filter [E.4 (c)]. Wash twice with 15 mL portions of water. Place the filter

in 10 mL of the potassium hydroxide solution [E.3 (b)] and dissolve the precipitate. Transfer the solution

quantitatively to a 100 mL one-mark volumetric flask and add to it 10.0 g of the sodium chloride [E.3(c)].

Dilute the solution to approximately 60 mL with water, swirl until the crystals are dissolved. Follow the

procedure described in E.5.4.2.

E.5.4.2 Determination. Add, in the order given, 5 mL of the sulphuric acid solution [E.3 (a)] and 5 mL of

the iron (II)/iron (III) solution [E.3 (d)]. Mix after each addition. Dilute with water to the mark and mix

well. Allow the solution to stand for 15 min. Adjust the apparatus to zero absorbance with respect to

water prior to each measurement. Measure the absorbance of the solution, using either the spectrometer

set at the wavelength of maximum absorbance (approximately 700 nm) or the photometer [E.4 (b)] fitted

with the filters specified.

E.6 Expression of results

Using the calibration curve (see E.5.3.3), determine the masses, in micrograms, of potassium hexacyanoferrate in the test solution and in the blank solution corresponding to the absorbance of the test solution. Calculate the water-soluble hexacyanoferrate (II) content, expressed as milligrams per kilogram of hexacyanoferrate Fe (CN)6 on a moisture free basis, using one of the following expressions, as

appropriate.

(a) Direct method

( m − m \ ( \

I 1 2 I × 500

× I 100

I × 211.96

m0 50 100 − H 422.39

(b) Filtration method

( m − m \ ( \

I 1 2 I × m0

I 100

100 − H I ×

211.96

422.39

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DJS 87:2017

where: m1 is the mass of potassium hexacyanoferrate found in the test solution (in µ g) (see E.5.4.2);

m2 is the mass of potassium hexacyanoferrate found in the blank test solution (E.5.2) (in µ g);

m0 is the mass of the test portion (g);

H is the moisture content determined in accordance with the requirements of appendix B (in % (m/m).

E.7 Precision

Comparative analyses on two samples, carried out by 11 laboratories, have given the following statistical

information:

(a) Mean (mg/kg) 3.09

(b) Standard deviation for repeatability (r) 0.083 (c)

Standard deviation 0.536

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DJS 87:2017

Appendix F

Determination of iron in salt

F.1 Reagents

(a) Standard iron (III) (ferric) solution. Dissolve 0.864 g of AR ammonium iron (III) sulphate in 100 mL

water, add 10 mL of concentrated HCl and dilute to 1 L. 1mL = 0.1 mg Fe.

(b) o-phenanthroline, 0.25% solution of the monohydrate in water.

(c) Sodium acetate, 0.2 M (0.2 N).

(d) Hydroxylamine hydrochloride, 10%.

(e) Bromophenol blue indicator.

F.2 Procedure

Take an aliquot of the unknown slightly acid solution containing 0.1 mg to 0.5 mg of iron and transfer it

to a 50 mL volumetric flask. Determine by the use of a similar aliquot containing a few drops of

bromophenol blue, the volume of sodium acetate solution required to bring the pH to 3.5 ± 1.0. Add the

same volume of acetate solution to the original aliquot and then 5 mL of the 10% hydroxylamine

hydrochloride and 5 mL of the o-phenanthroline reagent. Dilute to 50 mL, mix and measure the intensity

after 5 minutes to 10 minutes at 510 nm. Compare the intensity of the colour produced with standards

similarly prepared.

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DJS 87:2017

Appendix G

Determination of sulphate, calcium and magnesium in salt

G.l Reagents

(a) Barium chloride (BaCl2) solution (10%).

(b) Oxalic acid (H2C2O4) solution (10%).

(c) Ammonia (NH3) solution.

(d) Ammonium oxalate [(NH4)2C2O4] solution (1 %).

(e) Hydrochloric acid (HCl) (1: 1).

(f) Diammonium hydrogen orthophosphate, (NH4)2 HPO4.

(g) Ammonium hydroxide (NH4OH) solution (1:10).

(h) Methyl orange.

G.2 Procedure

G.2.1 Preparation of sample. Weigh about 20 g sample accurately and transfer to a 400-mL beaker

and dissolve in 200 mL HCl (1 + 3). Cover beaker, heat to boiling point, and continue boiling gently for

10 minutes. Filter the solution and wash residue with small amounts of hot water until filtrate is

chloride- free. Unite filtrate and washings, cool and dilute to 500 mL (solution A).

G.2.2 Sulphate determination

G.2.2.1 Procedure. Place 250 mL of solution A in a 400 mL beaker. Heat to boiling point and add a slight excess of hot 10% BaCl 2 solution drop wise while stirring. Concentrate by heating gently and

finally evaporate to dryness using a steam-bath. Facilitate removal of free acid by stirring partly dried residue. Wash precipitate by decantation with small amounts of hot water. Test filtrate for presence of

Ba. Wash precipitate on paper until filtrate is chloride-free. Dry and ignite the filter paper containing the

precipitate carefully over bunsen flame without inflaming the paper. Heat for 1 h periods to constant weight at 600 ºC in a furnace. Calculate the result on a moisture-free basis.

G.2.2.2 Calculation

% Sulphate =

weight of

BaSO4 × 4113

1 Original weight of

2

Sample × (100 − % moisture)

G.2.3 Calcium determination

G.2.3.1 Procedure. Place the remainder of solution A in a 400mL beaker. Add excess of 10% oxalic

acid solution (10 mL usually is enough). Add few drops of methyl orange and neutralize while hot by

17

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adding NH4OH (1:1) dropwise, stirring constantly. Add about 1 mL excess NH4OH, stir, and let it stand

in a warm place for 3 h. Decant through filter paper, reserving the filtrate for magnesium determination.

Test filtrate for calcium (Ca) with ammonium oxalate solution. Wash the precipitate in the beaker once

with 10 mL 1% ammonium oxalate solution, decanting through the filter paper. Reserve the filtrate and

washings (solution B). Dissolve precipitate on the paper with hot HCl (1:1). Using the same beaker;

dilute to 100 mL, add a little more oxalic acid solution and precipitate as before. Let the solution stand

for 3 h and filter and wash with 1% ammonium oxalate solution, reserving filtrate and washings as

before. Transfer the precipitate to a previously dried and weighed platinum crucible. Dry, ignite and heat

over a meker burner to constant weight. Report as percent Ca on water-free basis.

G.2.3.2 Calculation

% Calcium on water − free basis =

wt. CaC2 O4 × 3128.2

1 Original wt. of

2

sample × (100 − % moisture)

G.2.4 Magnesium determination

G.2.4.1 Procedure. Use the reserved combined filtrate and washings from the Ca determination (solution B). Concentrate the solution, if necessary, by boiling gently to about 200 mL (solution C); acidify with HCl (1:1) and add 2 g to 3 g (NH4)2HPO4 and enough HCI (1:1) to produce a clear solution

when all (NH4)2HPO4 is dissolved. When cold, make slightly alkaline with NH4OH, stirring constantly.

Add 2 mL excess NH4OH and let it stand for 12 h. Filter and wash 4 times by decantation with NH4OH

(1:10). Dissolve the precipitate in HCI (1:1), dilute to about 150 mL, add some (NH4)2HPO4 and

precipitate with NH4OH as before. Let stand for 12 h, filter and wash chloride-free with NH4OH (1:10).

Place in a weighed platinum crucible, char without inflaming and heat to constant weight in a furnace at 1 000 º C. Weigh as Mg2P2 O 7.

G.2.4.2 Calculation

% Magnesium = wt. .Mg 2 P2 O7 × 0.2184 × 100

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Appendix H

Determination of matter insoluble in water or in acid and preparation of principal solutions for

other determinations

H.1 Reagent

H.1.1 Silver nitrate, 5 g/L nitric solution.

Distilled water, or water of equivalent purity, shall be used in the test. Dissolve 0.5 g of silver nitrate in a

little water, add 10 mL of nitric acid solution p1.40 g/ml approximately, and dilute to 100 mL.

H.2 Apparatus

Ordinary laboratory apparatus and;

(a) filter crucible or funnel, glass or porcelain, approximately 30 mm diameter and of a porosity grade P 10

or P 16 (pore size index 4 µ m to16 µ m);

(b) electric oven, ventilated by convection and capable of being controlled at 110 ± 2°C;

(c) desiccator, containing silica gel, phosphorus pentoxide or a molecular sieve.

H.3 Sampling and samples

For methods of sampling and the number of samples to be taken for a given quantity of product, the

procedure described in ISO 2859 shall be followed.

H.4 Procedure

H.4.1 Test portion. Weigh, to the nearest 0.01 g, approximately 100 g of the test sample.

H.4.2 Determination. Place the test portion (H.4.1) in a 600 mL beaker and add 350 mL of water. Heat at

just below boiling point for 10 minutes, stirring constantly. Transfer the beaker, covered with a watch

glass, to a boiling water bath for 30 minutes. Cool to approximately 20°C. Filter by vacuum on the filter

crucible [H.2 (a)], previously dried at 110°C, cooled in the desiccator [H.2(c)], and weighed to the nearest

0.1 mg. Wash the insoluble matter, in groups of five successive washings, using 20 mL of water each time,

disconnecting the vacuum after each washing in order to bring the insoluble matter into suspension for

approximately 1 min before filtering, and checking for absence of chloride from the filtrate after the fifth, tenth or fifteenth washing. 10 mL of the washing water shall remain clear 5 minutes after adding 10 mL of the nitric silver nitrate solution (H.1.1). Cease washing as soon as the check indicates absence of chlorides.

Dry the crucible and its contents in the oven [H.2 (b)] controlled at 110 ± 2 °C for 1 h, cool in the

desiccator [H.2(c)] and weigh to the nearest 0.1 mg. Repeat this operation until two weighings differ by not

more than 0.2 mg.

NOTE. If the insoluble matter is so finely divided as to clog the filter, repeat the determination and add, after the 350 mL of water,

1.5 g, weighed to the nearest 0.1 mg, of a filter aid (Kieselguhr) of analytical quality. The minimum particle size of the filter aid

should be 15 µ m and it should be dried at about 110 0C to constant mass before use.

H.4.3 Preparation of the principal solution for other determinations (solution A). Quantitatively transfer

the filtrate obtained, after filtering and washing of the insoluble matter, to a 1 L one-mark volumetric flask.

Dilute with water to the mark and mix. Keep this solution for the other determinations.

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H.5 Expression of results

H.5.1 Method of calculation and formula. The matter insoluble in water is given, as a percentage by mass,

by the formula:

m1 − m2

m0

× 100

where:

mo is the mass, in grams, of the test portion;

m1 is the mass, in grams, of the filter crucible and insoluble matter; m2 is the mass, in grams, of the filter crucible alone.

NOTE. If a filter aid has been used, deduct its mass from m1 (see NOTE in H.4.2).

H.5.2 Repeatability and reproducibility. Comparative analyses on two samples in nineteen laboratories

have given the following statistical results:

Table 2. Statistical results of comparative analysis

Evaporated

salt

Marine

salt

Mean (percentage by mass)

Standard for repeatability (cr r)

Deviation for reproducibility (cr R )

0.001

0.0005

0.0008

0.044

0.002

0.008

DJS 87:2017

20

Appendix J

Determination of arsenic -Silver diethyl dithio-carbamate red complex absorptiometric method

J.l Principle

Arsenic reacts with a solution of silver diethyl dithio-carbamate, [AgS.CS.N (C2 H5 )2 ] in pyridine to form

a soluble red complex which has an adsorption maximum at 540 nm. The arsenic shall be in the trivalent

state in the sample which is secured by reducing the arsenate with potassium iodide and stannous chloride

in acid media. The arsenic is converted into arsine by the treatment of hydrochloric acid and zinc and

evolved arsine is absorbed in the reagent to form a red complex. Using any standard photoelectric

absorptiometer, absorption measurement is done at 540 nm, with coloured red complex solution against

blank reagent solution for total transmittance. From the transmittance or optical density obtained with

known arsenic content covering the range 0 µ g to 10 µ g (as 0 nm to 10 nm As), standard calibration graph

is prepared by plotting the percent transmittance or optical density or logarithm of per cent transmittance

(log T ) against known concentration. As it obeys Beer's Law, log T or the optical density is directly

proportional to the concentration and only a few points are required to establish the graph for the

determination of arsenic under the experimental condition.

J.2 Reagents

(a) Potassium iodide, 150 g/L solution. Store in a dark place.

(b) Stannous chloride solution.

(c) Zinc shots, arsenic-free.

(d) Silver diethyl dithio-carbamate, 5 g/L solution in pyridine. Dissolve 1 g of silver diethyl dithio-

carbamate (SDDC) in pyridine (relative density = 0.980 approx.) and dilute to 200 mL with this pyridine.

Store in a well-stoppered glass bottle protected from light. This solution is stable for 2 months.

NOTE. If suitable reagent is not available it may be prepared from sodium diethyl dithio-carbamate by the method given below:

(1) Purification of sodium diethyl dithio-carbamate. Dissolve 10g sodium diethyl dithio-carbamate [(C2 H2).N.CS2Na.3H2 O] in 35 mL of ethanol (95% v/v) and filter. Add 100 mL of diethyl ether to this solution with continual stirring.. Filter with suction, wash

the precipitate with ether and dry in air.

(2) Preparation of the reagent. Dissolve 2.25 g sodium diethyl dithio-carbamate in 100 mL water. Dissolve 1.7 g of silver nitrate in

100 mL water. Mix the two solutions slowly with continuous agitation. Keep the mixture at a temperature below 10 ºC (50 ºF). Filter with the aid of a suction pump and dry the product in vacuum at room temperature. Preserve in a cool place protected from

light.

This solution is unsatisfactory if the optical density is less than 0.03 µ g of arsenic using 5 mL of this solution.

J.3 Apparatus

The evolution and absorption apparatus as shown in figure 1 shall consist of the following:

(a) conical flask A, 100 mL for the evolution of arsine;

(b) connection tube B, to trap hydrogen sulphide;

(c) absorption tube C;

(d) spring clip, to secure the joint connecting B to C (may be either ground cone- socket joint or ball joint

with hooks);

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(e) spectrophotometer or photoelectric absorptiometer.

Figure 1. Apparatus for arsenic determination

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J.4 Procedure

J.4.1 Transfer 10 mL of the standard arsenic solution containing 10 µ g of arsenic and 10 mL of the

concentrated hydrochloric acid into a 100 mL conical flask A and dilute it approximately to 40 mL with

water. Add 2 mL of the potassium iodide solution and 0.5 mL of the stannous chloride solution. Mix and

allow to stand for 15 minutes. Place some dry lead acetate paper in the lower portion of the connection tube

B and glass wool (or cotton) moistened with lead acetate solution in its upper portion. Assemble the

apparatus. Transfer 5.0 mL of silver diethyl dithio-carbamate solution to the absorption tube C. After the

15-minute standing period, introduce 5 g of the zinc shots into the conical flask A and rapidly replace the

cone into the neck of the flask. Allow the reaction to continue for 45 minutes. Disconnect the absorption

tube C and tilt the absorber tube so that the reagent solution flows back and forth between the absorber and

bulb to dissolve any red complex and to thoroughly mix the solution. Transfer the solution to the

photometric cell. Absorption measurement is done at 540 nm with 5 mL coloured red complex solution in a

cell of 1 cm thickness against the blank reagent for total transmittance. Volume and optical path of the

comparison cell shall be same for both the measurements and may be adjusted to suit the instrument.

Alternatively, record its optical density at 540 nm as both are calibrated on the scale.

J.4.2 Transfer 10 g of the dried sample into the conical flask and carry out the procedure as described

above. With the absorbed solution, measure the percent transmittance or optical density at 540 nm against

total transmittance for the reagent. Since the colour is not stable, measurement of optical density or percent

transmittance shall be done immediately.

J.4.3 If it is desirable to know the exact amount of arsenic, determine the percent transmittance or optical

density for another standard solution containing 5 µ g of arsenic. Since it obeys Beer’s Law, draw a graph

plotting the logarithm of the percent transmittance (log T) or optical density determined for the standard

solution against arsenic content. Straight line is obtained passing through the points obtained for 0.5 µ g and

10 µ g of arsenic. From the graph, read the amounts of arsenic corresponding to the respective percent

transmittance or optical density of the sample taken and the blank solution.

J.5 Calculation

Arsenic content in the sample in µ g/g = 0.1(M1 – M2)

where:

M1 is mass in µ g in the sample; and M2 is mass in µ g in the blank.

DJS 87:2017

23

Appendix K

Method for the determination of copper in sodium chloride

K.1 Principle

This test describes a photometric method using zinc dibenzyldithiocarbamate for the determination of

copper in sodium chloride. The method is applicable to products having copper contents equal to or

greater than 0.01 mg/kg. The principle of this test method is the formation of a coloured complex by

reaction of the copper with zinc dibenzyldithiocarbamate and photometric measurement at a

wavelength of approximately 435 nm.

NOTE. By carrying out the determination in acid medium, interferences, especially from iron, manganese, nickel and cobalt,

are suppressed or much reduced.

K.2 Reagents

General. Use only reagents of recognized analytical grade.

(a) Water complying with grade 3 of BS EN ISO 3696.

(b) Carbon tetrachloride, redistilled.

(c) Hydrochloric acid, (HCl) 2 mol/L. Dilute 160 mL of hydrochloric acid, p = 1.19

g/mL, to 1L with water.

CAUTION. Always add acid slowly to water with stirring.

(d) Zinc dibenzyldithiocarbamate, 0.5 g/L solution in carbon tetrachloride. Dissolve 0.5 g of zinc

dibenzyldithiocarbamate in 100 mL of carbon tetrachloride [K.2 (b)].

(e) Copper stock solution, 0.100 g of Cu per L. Weigh, to the nearest 0.0001 g, 0.393 g of copper (II) sulphate pentahydrate (CuSO4.5H2O) and transfer to a 1L one- mark volumetric flask. Add

approximately 50 mL of water and swirl until the salt has dissolved. Add 50 mL of the hydrochloric acid solution [K.2 (c)], dilute with water to the mark and mix well. Make this solution each week.1 mL of this solution contains 100 µ g of Cu.

(f) Copper standard solution, 0.0010 g of Cu per L. Introduce 10.0 mL of the stock copper solution

[K.2 (e)] into a 1L one-mark volumetric flask, dilute with water to the mark and mix well. 1 mL of this

standard solution contains 1 µ g of Cu. Prepare this solution at the time of use.

K.3 Apparatus

(a) Ordinary laboratory apparatus.

(b) Spectrometer, or photometer, fitted with filters having a maximum transmission between 430 nm

and 440 nm.

(c) Burette, 25 mL, graduated in 0.02 mL.

K.4 Procedure

K.4.1 General. Wash all new glassware used in the determination as follows:

DJS 87:2017

24

(a) with brush and soap if the sides are greasy;

(b) with concentrated nitric acid, followed by several rinses with water.

Use the glassware a few times before carrying out an actual determination. Then keep exclusively for

the determination of copper.

CAUTION. Ensure that no trace of copper is introduced during the analysis by the reagents, the water

or the apparatus, especially the apparatus used in the preparation of the initial sample.

K.4.2 Test portion. Weigh, to the nearest 0.1 g, a test portion of approximately 100 g.

K.4.3 Blank test. At the same time as the determination, carry out a blank test following the same

procedure and using the same quantities of all the reagents used for the determination but omitting the

test portion.

K.4.4 Preparation of the calibration curve

K.4.4.1 Preparation of the standard colorimetric solutions. Introduce from the burette [K.3 (c)] into a

series of five 500 mL separating funnels, each containing 25 mL of the hydrochloric acid [K 2 (c)],

the volumes of the copper standard solution [K.2 (f)] shown in table 3.

NOTE. The calibration can be extended, if necessary. The curve is linear up to 50 µ g of Cu.

Table 3. Mass of copper in standard solutions

Volume of standard copper solution / mL

Corresponding mass of copper / µ g

0 *

2.5

5.0

7.5

10.0

0

2.5

5.0

7.5

10.0

*zero standard

K.4.4.2 Formation of the coloured complex. Dilute the contents of each separating funnel with water

to approximately 250 mL and mix. Add 25.0 mL of the zinc dibenzyldithiocarbamate solution [K.2

(d)]. Stopper, shake well for 1 minute and allow the layers to separate. Run the lower layer through a

hydrophobic filter paper into a cell with optical path length of 4 cm.

NOTE. Cells of path length 5 cm may be used if 4 cm cells are not available.

K.4.4.3 Photometric measurements. Adjust the apparatus to zero absorbance with respect to carbon

tetrachloride [K.2 (b)] prior to each measurement. Measure the absorbance of each solution in a cell

with optical path length of 4 cm (see NOTE to K.4.4.2), using the spectrometer [K.3 (b)] set at the

wavelength of maximum absorbance (approximately 435 nm) or the photometer fitted with the filters

specified. Deduct the absorbance of the zero standard from the absorbance obtained for each

colorimetric solution (see K.4.4.1).

NOTE. Carry out the measurements immediately after extraction in order to minimize the evaporation of the carbon

tetrachloride.

DJS 87:2017

25

K.4.4.4 Plotting the calibration curve. Plot a graph having, for example, the mass of copper contained

in the standard colorimetric solutions (see K.4.4.1) expressed in micrograms as abscissae and the

corresponding values of absorbance as ordinates. Prepare a new calibration curve whenever a new

stock solution [K.2 (e)] is prepared.

K.4.5 Determination

K.4.5.1 Preparation of the test solution. Add the test portion (K.4.2) to a 600 mL beaker, and add 350

mL of cold water and 50 mL of the hydrochloric acid [K.2 (c)]. Boil until the sample has completely

dissolved. Cool to approximately 20°C. Transfer the solution quantitatively to a 500 mL one-mark

volumetric flask, dilute with water to the mark and mix well.

NOTE. If the final solution is cloudy, filter it.

K.4.5.2 Formation of the coloured complex. Introduce an aliquot portion of the test solution (see

K.4.5.1) containing 0 to 10 µ g of copper into a 500 mL separate the funnel and add 25.0 mL of the

zinc dibenzyldithiocarbamate solution [K.2 (d)]. Stopper, shake well for 1 minute and allow the layers

to separate. Run out the lower layer through a hydrophobic filter paper into a cell of optical path

length of 4 cm.

NOTE. If cells of 5 cm path length have been used to prepare the calibration curve, then use cells of 5 cm path length for the

determination also.

K.4.5.3 Photometric measurements. Adjust the apparatus to zero absorbance with respect to carbon

tetrachloride (K.2 (b)] prior to each measurement. Measure the absorbance; the test solution (see

K.4.5.1) and the blank solution (see K.4.3) in a cell with optical path length of 4 cm (see NOTE to

K.4.4.2), using the spectrometer [K.3 (b)] set at the wavelength of maximum absorbance

(approximately 435 nm) or the photometer fitted with the filters described in K.3 (b).

Deduct the absorbance of the blank solution from the absorbance obtained for the sample.

K.5 Expression of results. Using the calibration curve (K.4.4.4), determine the mass, in

micrograms, of copper in the test solution and in the blank solution corresponding to the absorbance of

the zero standard.

Calculate the total copper content, expressed as mg per kg on a moisture free basis, using the

following expression:

(500 m1 ) × (V m0 )

100

100 − H

where:

m0 is the mass of the test portion (in g) (K.4.2);

m1 is the mass of copper found in the aliquot portion of the test solution (in µ g) (K.4.5.2); H is the moisture content determined in accordance with appendix B [in % (m/m)];

V is the volume, in mL, of the aliquot portion of the test solution (K.4.5.2).

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Appendix L

Method for the determination of lead in sodium chloride

L.1 Principle

This test describes a flame atomic absorption spectrometric (AAS) method for the determination of

total lead in sodium chloride. The principles of this test method are as follows:

(a) the dissolution of the sample in nitric acid solution;

(b) the complexation of certain metals, including lead, by ammonium pyrrolidine-1-

carbodithioate (APCD), and extraction of the metal complexes into chloroform and back-extraction

into nitric acid;

(c) the aspiration of the nitric acid solution into an acetylene/air flame;

(d) the measurement of the absorbance at a wavelength of approximately 283.3 nm, using an atomic

absorption spectrometer fitted with a lead hollow-cathode lamp.

L.2 Reagents

General. Unless otherwise stated, use only reagents of recognized analytical grade.

(a) Water complying with grade 3 of BS EN ISO 3696.

(b) Nitric acid, p = 1.40 g/mL, 945 g/mL HNO3 approximately.

(c) Chloroform, p = 1.48 g/mL.

(d) Ammonium pyrrolidine-1 -carbodithioate solution, special reagent for AAS. Dissolve

20 g of AAS grade APCD in 1 L of water and filter. Prepare this solution daily.

(e) Ammonia solution, p = 0.9 g/mL.

(f) Diammonium hydrogen citrate solution, 113 g/L solution. Dissolve 124 g of diammonium

hydrogen citrate in a 500 mL one-mark volumetric flask, dilute to the mark with water and mix.

Purify this solution as follows:

(1) Shake 100 mL of the solution with 10 mL of the APCD solution [L.2 (d)] and extract

three times respectively with 10 mL, 5 mL and 5 mL of the chloroform [L.2(c)].

(2) After the phase separation, following each extraction, back-extract the combined

organic extracts into nitric acid by running the organic layer into a previously dried

100 mL separating funnel [L.3(e)] containing 1.0 mL of the nitric acid [L.2(b)].

(3) Repeat the extraction and back-extraction procedure until when aspirating the nitric acid

extracts into the acetylene-air flame the absorbance measured at approximately 283.3 nm is lower

than 10 times the absorbance of 20 mL of chloroform extracted with a mixture of 1.0 mL of the

nitric acid [L 2(b)] and 9.0 mL of water.

(4) Transfer the purified solution to a 200 mL one-mark volumetric flask, add 20 mL of the

ammonia solution [L.2(e)], dilute with water to the mark and mix.

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(g) Lead stock solution, corresponding to 1000 mg/L Pb. Weigh, to the nearest 0.0001 g, 1.598 g of

lead nitrate, Pb(NO3)2, grind it and dissolve it in 10 mL of the nitric acid [L.2(b)]. Transfer the

solution quantitatively to a 1 L one-mark volumetric flask, and then dilute with water to the mark and mix.

NOTE 1. 1 mL of this solution contains 0.001 g of lead.

NOTE 2. A commercial stock solution for atomic absorption spectrometry of the same strength may also be used, if

available.

(h) Lead standard solution, corresponding to 10 mg/L Pb. Transfer 10.0 mL of the lead stock solution

[L.2(g)] to a 1L one-mark volumetric flask, add 1.0 mL of nitric acid [L.2(b)], and then dilute with

water to the mark and mix.

L.3 Apparatus

(a) Ordinary laboratory apparatus.

(b) Atomic absorption spectrometer, fitted with an acetylene-air burner and scale expansion facility.

NOTE. In order to reduce interferences caused by non-atomic absorption the use of a background correction device is

recommended.

(c) Lead hollow-cathode lamp.

(d) Separating funnels, 500 mL.

(e) Separating funnels, 100 mL.

L.4 Procedure

L.4.1 General. Wash all the glassware to be employed for this determination as follows, rinsing very

carefully with water after each operation:

(a) with a brush and detergent if the walls are greasy;

(b) with diluted nitric acid (1: 2).

NOTE. Ensure that no traces of lead are introduced during the analysis, taking care to avoid any contamination during the

sampling process and particularly at the grinding stage.

L.4.2 Test portion. Weigh, to the nearest 1 g, a test portion of 250g.

L.4.3 Test solution. Transfer the test portion (see L.4.2) to a 2 L beaker, add 850 mL of water and

swirl to dissolve.

L.4.4 Blank test. Transfer 850 mL water into a 2 L beaker to act as a blank solution.

L.4.5 Mineralization. To each 2 L beaker (see L.4.3 and L.4.4) add 10.0 mL of the nitric acid [L.2(b)]

and stir. Add some glass beads, heat to boiling point and boil gently for 30 minutes. Ensure that the

total volume never falls below 800 mL, adding more water if necessary. (The same volume to both

beakers.) Allow the solution to cool and transfer it quantitatively to a 1 L one-mark volumetric flask,

and then dilute with water to the mark and mix.

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L.4.6 Determination

L.4.6.1 Preparation of the standard matching solutions

L.4.6.1.1 Preparation of the standard matching solutions for the test solution. Transfer into each of

four 500 mL separating funnels [L.3 (d)] 200 mL of the mineralized test solution (see L.4.5) and the

volumes of the standard lead solution [L.2 (h)] indicated in table 4.

Complex and extract lead as described in L.4.6.2.2 to L.4.6.2.6.

Table 4. Mass of lead in standard solution

Standard matching

solution reference

number

Volume of the

standard lead solution

[L.2(h)]

/ mL

Corresponding mass of

lead / µ g

1*

2

3

4

0.0

2.5

5.0

10.0

0

25

50

100

*test solution

L4.6.1.2 Preparation of the standard matching solutions for the blank. Transfer to four 50 mL one-

mark volumetric flasks the volumes of the lead standard solution indicated in table 4. To each flask

add 5.0 mL of the nitric acid [L.2 (b)], dilute to the mark with water and mix.

Carry out the procedure as described in L.4.6.4.

L.4.6.2 Complexation and extraction of lead

L.4.6.2.1 Transfer 200 mL of the mineralized blank solution (see L.4.5) to a 500 mL separating

funnel [L.3 (d)].

L.4.6.2.2 Carry out the procedure with this 500 mL separating funnel (see L.4.6.2.1) and the

four standard matching solutions (see L.4 .6.1.1) in the following way:

(a) Add 20.0 mL of the diammonium hydrogen citrate solution [L.2 (f)].

(b) Add 5.0 mL of the APCD solution [L.2(d)] and shake for 30 s.

(c) Add 10.0 mL of the chloroform [L.2(c)] and shake vigorously for 1 minute.

L.4.6.2.3 After phase separation, run the organic layer into a previously dried 100 mL separating

funnel (L.3(e)) containing 1.0 mL of the nitric acid [L.2(b)].

L.4.6.2.4 Repeat this extraction procedure twice, using 5 mL of the chloroform [L.2(c)] on each

occasion and combining the organic phases in the separating funnel [L.3 (e)].

L.4.6.2.5 Shake the separating funnel vigorously for 30 s, add 9.0 mL of water and shake vigorously for 1 min.

L.4.6.2.6 When the layers have separated discard the lower organic layer and transfer the upper

aqueous layer to a dry tube.

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NOTE. The solution thus obtained may also be used for the determination of cadmium (see appendix N).

L.4.6.3 Apparatus setting. Equip the spectrometer [L.3 (b)] with the lead hollow-cathode lamp

[L.3(c)]. Set the lamp current, the slit and the pressure of acetylene and air according to the

instrument manufacturer’s instructions. Adjust the wavelength to that of the maximum absorption at

approximately 283.3 nm.

L.4.6.4 Spectrometric measurement. Aspirate all the final solutions (see L.4.6.2) and the standard

matching solutions for the blank test solution (see L.4.6.1.2) into the acetylene-air flame in the

following order, and at the same time, determine the absorbance of each:

(a) The four standard matching solutions for the blank test solution (see table 4).

(b) The final blank test solution (see L.4.4) after the complexation and extraction of lead.

(c) The three final standard matching solutions for the test solution after the complexation and

extraction of lead. (d) The final test solution after L.4.6.2 (number 1 from table 4).

L.5 Expression of results

L.5.1 Calculation

L.5.1.1 Calibration factors

L.5.1.1.1 Calibration factors for the test solution. The calibration factor (f1 ) of the three standard

matching solutions for the test solution (see table 4) is given by the following formula:

f1= m1

A1 − A2

where:

m1 is the mass of lead added to the standard matching solution (see numbers 2, 3 and 4 from table 4)

(in µ g);

A1 is the absorbance obtained for each final standard matching solution; A2 is the absorbance of the final test solution.

L.5.1.1.2 Calibration factor for the blank test solution. The calibration factor (f3 ) of the three

standard matching solutions for the blank test (see L.4.6.1.2) is given by the following formula:

f 3 = m1

A3 − A4

where:

m1 is the mass of lead added to the standard matching solution (see numbers 2, 3 and 4 from table 4) in µ g;

A3 is the absorbance obtained for each standard matching solution;

A4 is the absorbance of the standard matching solution. L.5.1.2 Average calibration factors. The average calibration factors are the arithmetic mean of each

group of the three calibration factors found in L.5.1.1.1.

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L.5.1.3 Lead content. The lead content, expressed in mg of lead (Pb) per kg of sodium chloride on a

moisture free basis, is given by the following formula:

1 T r

100 1

{(5 A2 × f1m ) − ( A5 × f 3m )} H m L l100 − H JJ

where:

A2 is the absorbance measured for the final test solution;

A5 is the absorbance measured for the final blank test solution; m is the mass (in g) of the test portion (see L.4.2); H is the moisture content determined in accordance with appendix B [in % (m/m)].

f1m is the average calibration factor (see L.5.1.2) for the test solution; f3m is the average calibration factor (see L.5.1.2) for the blank test solution.

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Appendix M

Method for the determination of mercury in sodium chloride

M.1 Principle

This method describes a cold vapour atomic absorption spectrometric method for the determination of

total mercury in sodium chloride. The method is applicable to products having mercury contents

greater than 0.02 mg of mercury per kg of sodium chloride. The principles are as follows:

(a) The dissolution of the sample in a mixture of water, sodium chlorate and hydrochloric acid.

(b) The conversion of all forms of mercury to ionic mercury (II) by the chlorine generated.

(c) The reduction of the excess of oxidant by hydroxylammonium chloride.

(d) The reduction of the mercury (II) to atomic mercury by tin (II) chloride.

(e) The entrainment of the mercury in a stream of gas and passage of the gas containing the mercury

vapour through a measuring cell.

(f) The measurement of the absorbance at a wavelength of approximately 253.7 nm using an atomic

absorption spectrometer fitted with a low-pressure mercury vapour lamp or a mercury hollow cathode

lamp.

M.2 Reagents

General. Unless otherwise stated, use only reagents of recognized analytical grade having the lowest

possible mercury content. Store all the reagent solutions in glass bottles.

(a) Water complying with grade 3 of BS EN ISO 3696.

(b) Sodium chloride, with a mercury content of lower than 0.02 mg/kg.

(c) Hydrochloric acid solution, containing 220 g/L H2O, approximately, (azeotropic mixture). Dilute

hydrochloric acid solution, p1.19 g/mL, (440 g/L HCl approximately) with an equal volume of water.

Add to each L, 5 mL of sulphuric acid, p 184 g/mL and distill.

(d) Sodium chlorate solution, 100 g/L solution. Dissolve 100 g of sodium chlorate, NaClO3, in 1 L of

water.

(e) Potassium dichromate solution, 4 g/L solution. Dissolve 4 g of potassium dichromate, K2Cr2O7, in

500 mL of water. Add 500 mL of nitric acid, p 1.40 g/mL and mix.

(f) Tin (II) chloride solution. Dissolve 25 g of tin (II) chloride dihydrate, SnC12.2H2O, in 50 mL of

warm hydrochloric acid solution, p 1.19 g/mL. Allow to cool and add 1 g to 2 g of metallic tin. Dilute with water to 250 mL and mix. Prepare this solution just before use. Pass a gentle stream of nitrogen through the solution for 30 min, in order to remove any mercury, before use.

NOTE. Avoid oxidation of solid tin (II) chloride by air.

(g) Hydroxylammonium chloride solution. Dissolve 100 g of hydroxylammonium chloride,

NH2OH.HCl, in 1 L water.

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(h) Mercury stock solution, corresponding to 1000 mg/L mercury. Weigh, to the nearest 1 mg, 1.354g

of mercury (II) chloride, HgCl2, into a 250 mL beaker. Add 50 mL of the hydrochloric acid solution

[M.2(c)] and 50 mL of the potassium dichromate solution [M.2 (e)]. Transfer the solution quantitatively to a 1 L one-mark volumetric flask, dilute with water to the mark and mix. Store this

solution in a cool, dark place and renew after 2 months.

(j) Mercury, standard solution, corresponding to 1 mg/L Hg. Prepare this solution on the day of use

by successive dilution of the stock solution (M.2 (h)). The final solution shall contain 50 mL of

potassium dichromate solution [M.2 (e)] per L of water.

(k) Charcoal.

(l) Drying agent, e.g. anhydrous calcium sulphate (3 mm to 5 mm, for desiccant use).

(m) Air or nitrogen. Use air or nitrogen containing no mercury or other components absorbing

radiation at a wavelength of approximately 253.7 nm. As an additional precaution, introduce a

charcoal filter before the aeration flask (see figure 2).

M.3 Apparatus

(a) Atomic absorption spectrometer, fitted with a low-pressure mercury vapour lamp or a mercury

hollow cathode lamp.

(b) Recorder or integrating read-out, giving full deflection in less than 1s.

(c) Measuring cell, minimum optical path length of 10 cm, with windows transparent to radiation at

253.7 nm.

(d) Aeration flask, for example a 100 mL gas washing bottle, with a sintered glass or fine jet inlet

tube and a mark at 60 mL.

NOTE. If several bottles are used, check that identical results are obtained with each.

(e) Four-way stopcock.

(f) Flow control system.

(g) Conical flasks, 100 mL.

(h) Adsorber, filled with the charcoal [M.2(k)], for the removal of mercury vapour from the

exhaust gases. Length approximately 100 mm, internal diameter approximately 15 mm.

(j) Adsorber, filled with drying agent [M.2(l)]. Length approximately 100 mm, internal diameter

approximately 15 mm.

NOTE. An example of a suitable apparatus is shown in figure 2. This depicts an open-circuit measuring system and

includes apparatus listed in M.3

M.4 Procedure

M.4.1 General. Wash all glassware not previously used for this determination, including flasks used

for reagents and samples, as follows, rinsing with water after each operation:

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(a) with a brush and detergent if the walls are greasy;

(b) with aqua regia or with nitric acid solution, p 1.42 g/mL.

Before using the glassware thus washed for actual determinations, check it by carrying out several

blank tests until satisfactory results are obtained. Thereafter use such glassware for mercury

determinations only. After each use treat the aeration flasks with the potassium dichromate solution

[M.2(d)] in order to oxidize any traces of tin (II) that they may contain. Traces of tin (IV) oxide

which may adhere to the walls of the aeration flask are removed by rinsing with hydrochloric acid p 1.19 g/L. All connecting tubes shall be as short as possible, in order to reduce adsorption of mercury.

Keep the aeration flasks full of water when not in use.

M.4.2 Test portion. Weigh, to the nearest 0.1 g, approximately 10 g of the test sample, transfer it to a

100 mL conical flask and add 30 mL of water. Carry out the determination described in M.4.5.

NOTE. The sample solution prepared according to the requirements of appendix H should not be used, as in this solution

mercury losses will occur. Samples should be mixed as well as possible and the test portion should be taken directly from

the solid sample blend.

M.4.3 Blank test. Transfer to a 100 mL conical flask 30 mL of water. Proceed in accordance with

M.4.5, using the same quantities of all the reagents as used for the determination.

M.4.4 Preparation of the standard matching solutions. To a series of six conical flasks [M.3 (g)] add

the same quantity of the sodium chloride [M.2 (b)] as the test portion (M.4.2), 30 mL of water and the

volumes of the standard mercury solution [M.2 (j)] indicated in table 5. Carry out the determination

described in M.4.5

NOTE 1. Because of matrix effects, dependent on the concentration of sodium chloride in the solution during aeration

(M.4.3), a quantity of sodium chloride equal to the test portion (M.4.2) should be taken for the preparation of standard

matching solutions.

NOTE 2. Samples of unknown composition should be tested for the presence of matrix effects caused by components present other than sodium chloride, using the method of standard additions.

M.4.5 Determination

M.4.5.1 Mineralization. Add to each of the conical flasks (see M.4.2, M.4.3 and M.4.4) some glass

beads and 4.0 mL of the hydrochloric acid solution [M.2(c)] and 3.0 mL of the sodium chlorate

solution [M.2(d)]. Dissolve the sodium chloride, heat to boiling point, continue boiling for 5 min and

allow to cool to room temperature. Transfer the solution quantitatively to a 100 mL one-mark

volumetric flask, and then dilute with water to the mark and mix. Immediately before the

measurement described in M.4.5.3, transfer 10.0 mL of this solution to the aeration flask, followed by

3 mL of the hydroxylammonium chloride solution [M.2 (g)].

M.4.5.2 Apparatus settings. The settings of the atomic absorption spectrometer are as follows:

Air or nitrogen flow: 60 L/h Wavelength: 253.7 nm

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Table 5. Mass of mercury in standard solutions

Volume of standard mercury solution [M2 (h)]/ mL

Corresponding mass of mercury / µ g

0.0 *

0.5

1.0

1.5

2.0

3.0

0

0.5

1.0

1.5

2.0

3.0

* zero standard

Adjust the spectrometer [M.3(a)] according to the manufacturer’s instructions.

M.4.5.3 Measurement. Dilute the contents of the aeration flask to the 60 mL mark with water. Add 2

mL of the tin (II) chloride solution [M.2 (f)] and immediately connect the flask to the apparatus (see

figure 2). Swirl to mix and allow to stand for some minutes. Pass air or nitrogen [M.2 (m)] through

the aeration flask by manipulating the four-way stopcock. Continue the gas flow until no mercury is

left in the system then switch off the gas flow and remove the aeration flask.

M.4.5.4 Preparation of the calibration curve. Deduct the absorbance of the zero standard from the

absorbance obtained for the other standards. Plot a graph having, for example, the mass of mercury

contained in the standard matching solutions, expressed in micrograms, with abscissae and the

corresponding values of absorbance as ordinates.

Figure 2. Typical apparatus for determination of mercury by atomic absorption spectrometry

Key

A is the atomic absorption spectrometer B is the mercury hollow-cathode lamp or low-pressure mercury vapour lamp

C is the recorder or maximum deflection indicator

D is the measuring cell E is the aeration flask with sintered glass inlet or pointed immersion tube

F is the four-way stopcock G is the flow control system, e.g. pressure regulator, needle valve and flow meter

H is the adsorption tube with charcoal

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I is the adsorption tube with drying agent

M.5 Expression of results

Using the calibration curve (see M.4.5.4), determine the mass, in micrograms, of mercury in the test

solution and in the blank solution corresponding to the absorbance of the zero standard.

Calculate the mercury content, expressed in mg of mercury (Hg) per kg on a moisture free basis,

using the following expression:

m − m 100 1 2 ×

m0

100 − H

where:

m1 is the mass of mercury in the test portion (see M.4.2) (in µ g);

m2 is the mass of mercury in the blank solution (see M.4.3 ) (in µ g); m0 is the mass of the test portion (M.4.2) (in g); H is the moisture content as determined in accordance with appendix B (in % (m/m)).

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Appendix N

Method for the determination of cadmium in sodium chloride

N.1 Principle

This test describes a flame atomic absorption spectrometric (AAS) method for the determination of

total cadmium in sodium chloride. The principles of this test are as follows:

(a) The mineralization of cadmium and dissolution of the sample in nitric acid solution.

(b) The complexation of the cadmium and certain other metals by ammonium pyrrolidine-1-

carbodithioate (APCD), and extraction of the metal complexes into chloroform and back-extraction

into nitric acid.

(c) Aspiration of the nitric acid solution into an acetylene-air flame.

(d) Measurement of the absorbance at a wavelength of about 228.8 nm, using an atomic absorption

spectrometer fitted with a cadmium hollow-cathode lamp.

N.2 Reagents

General. Unless otherwise stated, use only reagents of recognized analytical grade.

(a) Water complying with grade 3 of BS EN ISO 3696.

(b) Nitric acid, p 1.40 g/mL, 945 g/L HNO3 approximately.

(c) Chloroform, p 1.481g/mL.

(d) Ammonium pyrrolidine-1 -carbodithioate (APCD) solution, special reagent for AAS. Dissolve 20

g AAS grade APCD in 1 L of water and filter. Prepare this solution daily.

(e) Ammonia solution, p 0.9 g/mL.

(f) Diammonium hydrogen citrate solution, 113 g/L solution.

(1) Dissolve 124 g diammonium hydrogen citrate in a 500 mL one-mark volumetric flask, dilute

with water to the mark and mix. Purify this solution as follows: (i) Shake 100 mL of the solution with 10 mL of the APCD solution (N.2(d) and extract three times respectively with 10 mL, 5 ml and 5 mL of the chloroform [N.2(c)].

(2) Back-extract the combined organic extracts into nitric acid, as follows:

(i) After the phase separation following each extraction, run the organic layer into a previously

dried 100 mL separating funnel [N.3(e)] containing 1.0 mL of nitric acid [N.2(b)].

(3) Repeat the extraction and back extraction procedure until, when aspirating the

nitric extracts into the acetylene-air flame, the absorbance measured at approximately

228.8 nm is lower than 10 times the absorbance of 20 mL of chloroform extracted

into a mixture of 1.0 mL nitric acid [N.2 (b)] and 9.0 mL water.

(4) Transfer 100 mL of the purified solution into a 200 mL one-mark volumetric flask, add 20

mL ammonia solution [N.2 (e)], and then dilute with water to the mark and mix.

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(g) Cadmium, stock solution, corresponding to 1000 mg/L. Weigh, to the nearest 0.1 g, 1.000 g of

cadmium metal strip or granules (99.99 %) and dissolve them in 10 mL of the nitric acid [N.2(b)].

Transfer the solution quantitatively to a 1 L one-mark volumetric flask, and then dilute with water to

the mark and mix.

NOTE 1. 1 mL of this solution contains 1 mg of lead.

NOTE 2. A commercial stock solution for atomic absorption spectrometry of the same strength may also be used if

available.

(h) Cadmium, standard solution, corresponding to 5 mg/L.

Transfer 5.0 mL of the stock solution (N.2(g)) to a 1 L one-mark volumetric flask, add 1.0 mL of the

nitric acid [N.2(b)], and then dilute with water to the mark and mix.

N.3 Apparatus

(a) Ordinary laboratory apparatus.

(b) Atomic absorption spectrometer, fitted with an acetylene-air burner and scale expansion facility.

NOTE. In order to reduce the interferences caused by non-atomic absorption the use of a background correction device is

recommended.

(c) Cadmium hollow-cathode lamp.

(d) Separating funnels of 500 mL capacity.

(e) Separating funnels of 100 mL capacity.

N.4 Procedure

N.4.1 General. Wash all the glassware to be employed for this determination as follows, rinsing very

carefully with water after each operation:

(a) with a brush and detergent if the walls are greasy;

(b) with diluted nitric acid (1+2).

NOTE. Ensure that no traces of cadmium are introduced during the analysis, taking care to avoid any contamination by

traces of cadmium during the sampling process.

N.4.2 Test portion. Weigh, to the nearest 1 g, a test portion of 250 g.

N.4.3 Test solution. Transfer the test portion (see N.4.2) into a 2 L beaker, add 850 mL of water and

stir to dissolve.

N.4.4 Blank test. Transfer 850 mL water into a 2 L beaker to act as a blank solution.

N.4.5 Mineralization. To each 2 L beaker (see N.4.3 and N.4.4) add 10.0 mL of the nitric acid

[N.2(b)] and stir. Add some glass beads, heat to the boil and boil gently for 30 min. Ensure that the

total volume never falls below 800 mL, adding more water if necessary. (The same volume to both

beakers). Allow the solution to cool and transfer it quantitatively to a 1 L one-mark volumetric flask,

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and then dilute with water to the mark and mix.

N.4.6 Determination

N.4.6.1 Preparation of the standard matching solutions

N.4.6.1.1 Preparation of the standard matching solution for the test solution. Transfer into each of

four 500 mL separating funnels [N.3(d)] 200 mL of the mineralized test solution (see N.4.5) and the

volumes of the standard cadmium solution [N.2 (h)] indicated in table 6.

Table 6. Mass of cadmium in standard solution

Standard matching

solution reference

number

Volume of the standard

solution [N.2 (h)] / mL

Corresponding mass

of cadmium / µ g

1* 2

3 4

0.00 0.50

1.00 2.00

0.0 2.5

5.0 10.0

*test solution

Complex and extract cadmium as described in N.4.6.2.2 to N.4.6.2.6.

N.4.6.1.2 Preparation of the standard matching solutions for the blank. Transfer to four 50 mL one-

mark volumetric flasks the volumes of the standard cadmium solution [N.2 (h)] indicated in table 6.

To each flask add 5.0 mL of nitric acid [N.2(b)], and then dilute with water to the mark and mix.

Carry out the procedure described in N.4.6.4.

N.4.6.2 Complexation and extraction of cadmium

N.4.6.2.1 Transfer 200 mL of the mineralized blank solution (see N.4.5) to a 500 mL separating

funnel [N.3(e)].

N.4.6.2.2 Carry out the procedure with this 500 mL separator funnel and the four 500 mL separating

funnels from N.4.6.1.1 as follows:

(a) Add 20.0 mL of the diammonium hydrogen citrate solution [N.2 (f)].

(b) Add 5.0 mL of the APCD solution [N.3 (d)], shake for 30 s.

(c) Add 10.0 mL of the chloroform [N.2 (c)], shake vigorously for 1 min.

N.4.6.2.3 After phase separation run the organic layer into a previously dried 100 mL separating

funnel [N.3 (e)] containing 1.0 mL of nitric acid [N.2(b)].

N.4.6.2.4 Repeat this extraction procedure twice, using 5 mL of chloroform [N.2(c)] on each occasion

and combining the organic phases in the separating funnel [N.3 (e)].

N.4.6.2.5 Shake the separating funnel vigorously for 30s, add 9.0 mL of water and shake vigorously

for 1 min.

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N.4.6.2.6 When the layers have separated discard the lower organic layer and transfer the upper

aqueous layer to a dry tube.

NOTE. The solution thus obtained may also be used for the determination of lead. (appendix L)

N.4.6.3 Apparatus setting. Equip the spectrometer [N.3(b)] with the cadmium lamp [N.3(c)]. Set the

lamp current, the slit and the pressure of acetylene and air according to the instrument manufacturer’s

instructions. Adjust the wavelength to that of the maximum absorption at approximately 228.8 nm.

N.4.6.4 Spectrometric measurements. Aspirate all the final solutions (see N.4.6.2) and the standard

matching solutions for the blank test solution (see N.4.6.1.2) into the acetylene-air flame in the

following order, and at the same time, determine the absorbance of each:

(a) The four standard matching solutions for the blank test solution (see table 6).

(b) The final blank test solution (N.4.4) after the complexation and extraction.

(c) The three final standard matching solutions for the test solution after the complexation and

extraction of cadium (numbers 2, 3 and 4 from table 6).

(d) The final test solution after the complexation and extraction of cadium (number 1 from table 5).

Aspirate water after each measurement.

N.5 Expression of results

N.5.1 Calculation

N.5.1.1 Calibration factors

N.5.1.1.1 Calibration factors for the test solution. The calibration factors (f1) of the three standard

matching solutions for the test solution (see table 6) is given by the following formula:

f1 = m1

A1 − A2

where:

m1 is the mass of cadmium added to the standard matching solution (see numbers 2, 3 and 4 from

table 6) (in µ g);

A1 is the absorbance obtained for each final standard matching solution; A2 is the absorbance of the final test solution.

N.5.1.1.2 Calibration factor for the blank test solution. The calibration factor (f3) of the three standard

matching solutions for the blank test (see N.4.6.1.2) is given by the following formula:

f 3 = m1

A3 − A4

where:

ml is the mass of cadmium added to the standard matching solution (see numbers 2,3 and 4 from table 6) (in µ g);

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1 r

A3 is the absorbance obtained for each standard matching solution;

A4 is the absorbance of the standard matching solution. N.5.1.2 Average calibration factors. The average calibration factors are the arithmetic mean of each

group of the three calibration factors found in N.5.1.1.1.

N.5.1.3 Cadmium content. The cadmium content, expressed in mg of cadmium (Cd) per kg of sodium

chloride on a moisture free basis, is given by the following formula:

T {(5 A2 ×

f1m ) − ( A5 ×

f 3m ) }H 100 1

m L l100 − H JJ where:

A2 is the absorbance measured for the final test solution;

A5 is the absorbance measured for the final blank test solution; f1m is the average calibration factor (see N.5.1.2) for the test solution; f3m is the average calibration factor (see N.5.1.2) for the blank test solution. m is the mass of the test portion (N.4.2) (in g);

H is the moisture content, determined in accordance with the requirements in appendix B [in %

(m/m)].

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Appendix P

Sampling plan for salt

P.1 Scale of sampling

P.1.1 The number of packages to be selected from the lot or batch shall depend upon the size of the

lot and shall be in accordance with table 7. This plan was taken from ISO 2859 using Inspection

Level S2.

Table 7. Sampling size

Lot or batch size Number of packages to be selected

2 to 25

26 to 150

151 to 1200

1201 to 35000

Over 35 000

2

3

5

8

13

P.1.2 These packages shall be selected at random from the lot; and to ensure randomness of selection,

a random number table may be used.

P.2 Preparation of test samples.

From each package selected in accordance with P.1.1, a portion of the material (dependent on the

number of tests to be done) shall be drawn with a suitable instrument. The portions shall be mixed

thoroughly to form a composite sample. This composite sample shall then be divided into the required

number of test samples.

P.3 Criteria for conformity

The lot shall be considered as conforming to this standard if test results satisfy the requirements

detailed in clause 4.

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Appendix Q

Volumetric conversion table (as they occur in sequence)

0.1 N

0.1 N Silver nitrate (AgNO3)

Hydrochloric acid (HCl)

0.1M AgNO3

0.1 M HCl

0.5 N 0.1 N

Sulphuric acid (H2 SO4) Potassium hydroxide (KOH)

0.25 M H2 SO4

0.1M KOH

0.2 N 0.1 N

Sodium acetate (CH3 COONa) Sodium thiosulphate (Na2 S2 O3)

0.2 M CH3 COONa 0.05 M Na2 S2 O3

Standards Council

The Standards Council is the controlling body of the Bureau of Standards Jamaica and is responsible for the policy and general

administration of the Bureau.

The Council is appointed by the Minister in the manner provided for in the Standards Act, 1969. Using its powers in the Standards

Act, the Council appoints committees for specified purposes.

The Standards Act, 1969 sets out the duties of the Council and the steps to be followed for the formulation of a standard.

Preparation of standards documents

The following is an outline of the procedure which must be followed in the preparation of documents:

1. The preparation of standards documents is undertaken upon the Standard Council’s authorisation. This may arise out of

representation from national organisations or existing Bureau of Standards’ Committees of Bureau staff. If the project is

approved it is referred to the appropriate sectional committee or if none exists a new committee is formed, or the project is allotted to the Bureau’s staff.

2. If necessary, when the final draft of a standard is ready, the Council authorises an approach to the Minister in order to obtain the formal concurrence of any other Minister who may be responsible for any area which the standard may affect.

3. The draft document is made available to the general public for comments. All interested parties, by means of a notice in the Press, are invited to comment. In addition, copies are forwarded to those known, interested in the subject.

4. The Committee considers all the comments received and recommends a final document to the Standards Council

5. The Standards Council recommends the document to the Minister for publication.

6. The Minister approves the recommendation of the Standards Council.

7. The declaration of the standard is gazetted and copies placed on sale.

8. On the recommendation of the Standards Council the Minister may declare a standard compulsory.

9. Amendments to and revisions of standards normally require the same procedure as is applied to the preparation of the

original standard.

Overseas standards documents

The Bureau of Standards Jamaica maintains a reference library which includes the standards of many overseas standards

organisations. These standards can be inspected upon request.

The Bureau can supply on demand copies of standards produced by some national standards bodies and is the agency for the sale of

standards produced by the International Organization for Standardization (ISO) members.

Application to use the reference library and to purchase Jamaican and other standards documents should be addressed to:

Bureau of Standards Jamaica

6 Winchester Road P.O. Box 113,

Kingston 10

JAMAICA, W. I.