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GB 5009.44-2016National food safety standard Determination of chloride in foods (English PDF)

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Issued by

National Health and Family Planning Commission of People’s Republic of China

Level / Type

National · Mandatory

Issue date

August 31, 2016

Implementation date

March 1, 2017

Scope

GB 5009.44-2016 (National food safety standard Determination of chloride in foods) is available as an English-translated PDF.

GB 5009.44-2016 — This standard specifies determination methods of chloride in foods by the potentiometric titration method, the Volhard method (indirect precipitation titration method), AND the argentometric method (moles method or direct titration method).

The potentiometric titration method of this standard is applicable to the determination of chloride in various types of foods. The Volhard method (indirect precipitation titration method) and the argentometric method (the moles or direct titration method) of this standard do not apply to the determination of chloride in deep-color foods. Method I. Potentiometric titration method

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Document preview — GB 5009.44-2016

National Standard of the People's Republic of China

Issued by: National Health and Family Planning Commission of People’s Republic of China

Foreword...4
1 Scope...5
2 Principles...5
3 Reagents and materials...5
4 Instruments and apparatuses...8
5 Analysis procedures...8
6 Analysis result representation...11
7 Precision...12
8 Others...12
9 Principles...12
10 Reagents and materials...12
11 Instruments and equipment...15
12 Analysis procedures...15
13 Analysis results representation...16
14 Precision...17
15 Others...17
16 Principles...17
17 Reagents and materials...18
18 Instruments and equipment...19
19 Analysis procedures...19
20 Analysis result representation...20
21 Precision...21
22 Others...21

Foreword

This standard replaces GB 5413.24-2010 "National food safety standard -

Determination of chlorine in foods for infants and young children, milk and milk

products", GB/T 12457-2008 "Determination of sodium chloride in foods", GB/T

15667-1995 "Fruits, vegetables and their products - Determination of chloride

content", GB/T 9695.8-2008 "Meat and meat products - Determination of

chloride content", GB/T 22427.12-2008 "Starches and derived products -

Determination of chloride content", AND the determination of "14.2 Salt" in GB/T

5009.44-2003 "Method for analysis of hygienic standard of meat and meat

products".

This standard will integrate the above standards, with the main modifications

are as follows.

- MODIFY the standard name into "National food safety standard -

Determination of chloride in foods";

- Based on the principle of chloride determination, three methods are

integrated. potentiometric titration method, Volhard method (indirect

precipitation titration method), AND argentometric method (moles method

or direct titration method);

- DELETE the original methods of determination based on food category;

- ADD the sonication procedures.

National food safety standard

Determination of chloride in foods

1 Scope

This standard specifies determination methods of chloride in foods by the

potentiometric titration method, the Volhard method (indirect precipitation

titration method), AND the argentometric method (moles method or direct

titration method).

The potentiometric titration method of this standard is applicable to the

determination of chloride in various types of foods.

The Volhard method (indirect precipitation titration method) and the

argentometric method (the moles or direct titration method) of this standard do

not apply to the determination of chloride in deep-color foods.

Method I. Potentiometric titration method

2 Principles

After the sample was acidified, ADD acetone; USE the glass electrode as the

reference electrode AND the silver electrode as the indicator electrode. USE

the silver nitrate standard titration solution to titrate the chloride in the test

solution. Based on the "jump" of the potential, DETERMINE the titration end

point. Based on the consumption of the silver nitrate standard titration solution,

CALCULATE the chloride content in the food.

3 Reagents and materials

Unless otherwise indicated, the reagents used in this method are of analytical

pure AND the water is level III water as specified in GB/T 6682.

3.1 Reagents

3.3 Reagent preparation

3.3.1 Precipitant I. WEIGH 106 g of potassium ferrocyanide; ADD water to

dissolve it and make its volume reach to 1 L; MIX it uniformly.

3.4.2 Silver nitrate standard titration solution (0.02 mol/L). WEIGH 3.40 g of

silver nitrate (accurate to 0.01 g) into a small beaker; USE a small amount of

nitric acid to dissolve it; TRANSFER it into a 1000 mL brown volumetric flask;

USE water to make it reach to the volume; SHAKE to make it uniform;

3.4.3 Calibration (second derivative method). PIPETTE 10.00 mL of 0.01000

mol/L sodium chloride reference solution into a 50 mL beaker; ADD 0.2 mL of

nitric acid solution and 25 mL of acetone. IMMERSE the glass electrode and

the silver electrode in the solution;

3.4.4 Determination of the titration end point. Based on the titration record

(3.4.3), USE the volume (V') and the potential value (E) of the silver nitrate

standard titration solution in accordance with the example as shown in Table

A.1, to calculate deltaE, deltaV, first derivative and second derivative in the listing

method. OR otherwise USE the potentiometric titrator for automatic titration,

and RECORD the volume and potential values of the silver nitrate standard

titration solution.

4 Instruments and apparatuses

4.1 Tissue stamping machine.

4.2 Shredder.

4.3 Mortar.

4.4 Vortex oscillator.

4.5 Ultrasonic cleaner.

4.9 Glass electrode.

4.10 Silver electrode, or composite electrode.

4.11 Electromagnetic stirrer.

5 Analysis procedures

5.1 Test specimen preparation

5.1.1 Powder, paste or liquid sample

TAKE at least 200 g of representative sample; MIX it uniformly; PLACE it in a

sealed glass vessel.

5.1.2 Massive or granular solid sample

TAKE at least 200 g of representative sample; USE shredder to crush it or USE

mortar to grind it fine; PLACE it in a sealed glass vessel.

5.2 Preparation of sample solution

5.2.1 Infant food and dairy products

WEIGH 10 g of uniformly mixed test specimen (accurate to 1 mg) and PLACE

it into a 100 mL colorimetric tube with stopper; ADD 50 mL of hot water of about

70 °C; SHAKE to disperse the test specimen; BOIL it in water bath for 15 min

and SHAKE it from time to time; TAKE it out; MAKE it subjected to ultrasonic

treatment for 20 min; COOL it to room temperature;

5.2.2 Protein, high-starch content vegetable products, and starch products

5.2.3 General vegetable products and pickled products

WEIGH about 10 g of test specimen (accurate to 1 mg) into a 100 mL

colorimetric tube with stopper; ADD 50 mL of hot water of about 70 °C; SHAKE

it for 5 min (OR use vortex oscillator to oscillate it for 5 min);

5.6 Fresh (frozen) meat, sausages, sauced meats, meats, barbecues and

hams

5.3 Determination

PIPETTE 10.00 mL of test solution (5.2) (V2) into a 50 mL beaker; ADD 5 mL of

nitric acid and 25 mL of acetone. IMMERSE the glass electrode and silver

electrode into the solution; START the electromagnetic stirrer. USE the acid

burette to drip V' mL of silver nitrate standard titration solution (90% of the

required amount); MEASURE the potential value (E) of the solution.

6 Analysis result representation

The chloride content in food is calculated in accordance with the equation (3).

7 Precision

The absolute difference between the two independent test results obtained

under repeatability conditions shall not exceed 5% of the arithmetical mean.

8 Others

If calculated based on the weighed sample of 10 g and constant volume of 100

mL, the limit of quantification (LOQ) is 0.008% (calculated as Cl-).

Method II.

9 Principles

MAKE the sample subjected to dissolving in water or hot water, precipitated

protein, and acid treatment; ADD excess silver nitrate solution; USE the

ammonium sulfate as an indicator; USE the potassium thiocyanate standard

titration solution to titrate the excessive silver nitrate.

10 Reagents and materials

Unless otherwise specified, the reagents used in this method are of analytical

pure and water is level III water as specified in GB/T 6682.

10.1 Reagent

10.2 Standard substance

Baseline sodium chloride (NaCl), purity >= 99.8%.

10.3 Reagent preparation

10.4 Preparation and calibration of standard solutions

10.4.1 Silver nitrate standard titration solution (0.1 mol/L). WEIGH 17 g of silver

nitrate; DISSOLVE it into a small amount of nitric acid; TRANSFER it into a

1000 mL brown volumetric flask; USE water to dilute it to the mark; SHAKE it

uniformly; TRANSFER it into a brown reagent bottle for storage. OR otherwise

PURCHASE the silver nitrate standard titration solution with certificate.

10.4.3 Determination of the volumetric ratio of silver nitrate standard titration

solution and potassium thiocyanate standard titration solution.

10.4.4 Calibration of silver nitrate standard titration solution (0.1 mol/L) and

potassium thiocyanate standard titration solution (0.1 mol/L). WEIGH 0.10 g of

sodium chloride which had been ignited at 500 °C ~ 600 °C to constant weight

(accurate to 0.1 mg);

11 Instruments and equipment

Same as 4.1 ~ 4.7 and 4.13.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 21 pages — is available in the English PDF.

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