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GB 5009.92-2016National food safety standard - Determination of calcium in foods (English PDF)

食品安全国家标准食品中钙的测定

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Issued by

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

Level / Type

National · Mandatory

Issue date

December 23, 2016

Implementation date

June 23, 2017

Scope

GB 5009.92-2016 is the English-translated version of 食品安全国家标准食品中钙的测定.

GB 5009.92-2016 — This Standard specifies the determination of calcium in foods by flame atomic absorption spectrometry, titration, inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry.

This Standard applies to the determination of calcium content in foods. Method 1 -- Flame atomic absorption spectrometry

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Document preview — GB 5009.92-2016

National Standard of the People's Republic of China

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

Foreword...3
1 Scope...4
2 Principle...4
3 Reagents and materials...4
4 Instruments and equipment...5
5 Analysis procedure...6
6 Expression of analysis results...8
7 Precision...9
8 Others...9
9 Principle...9
10 Reagents and materials...9
11 Instruments and equipment...10
12 Analysis procedure...10
13 Expression of analysis results...11
14 Precision...12
15 Others...12
Annex A Microwave digestion temperature rise program reference conditions...13
Annex B Flame atomic absorption spectrometry reference conditions...14

Foreword

This Standard replaces the determination method for calcium in GB/T 5009.92-2003

"Determination of calcium in foods", GB 5413.21-2010 "National food safety standard

- Determination of calcium, iron, zinc, sodium, potassium, magnesium, copper and

manganese in foods for infants and young children, milk and milk products", GB/T

23375-2009 "Determination of copper, iron, zinc, calcium, magnesium and

phosphorus content in vegetables and derived products", GB/T 14609-2008

"Inspection of grain and oils - Determination of copper, iron, manganese, zinc, calcium,

magnesium in cereals and derived products by atomic absorption and flame

spectrophotometry", GB/T 14610-2008 "Inspection of grain and oils - Determination of

calcium in cereals and cereal products", GB/T 9695.13-2009 "Meat and meat products

- Method for Determination of calcium content" and NY 82.19-1988 "Determination of

fruit juice - Determination of calcium and magnesium".

Compare this Standard with GB/T 5009.92-2003, the main changes are as follows.

- MODIFY the standard name TO "National food safety standard - Determination of

calcium in foods";

- ADD the microwave digestion, pressure tank digestion;

- MODIFY the flame atomic absorption spectrometry and EDTA titration;

- ADD the inductively coupled plasma emission spectrometry;

- ADD the inductively coupled plasma mass spectrometry.

National food safety standard -

Determination of calcium in foods

1 Scope

This Standard specifies the determination of calcium in foods by flame atomic

absorption spectrometry, titration, inductively coupled plasma atomic emission

spectrometry and inductively coupled plasma mass spectrometry.

This Standard applies to the determination of calcium content in foods.

Method 1 -- Flame atomic absorption spectrometry

2 Principle

After the sample is digested, add lanthanum solution as the releasing agent, atomize

by atomic absorption flame, and measure the absorbance value at 422.7 nm, which is

proportional to the calcium content in a certain concentration range. Compare with the

standard series.

3 Reagents and materials

Unless otherwise specified, the reagents used in this method are excellent regents,

and the water is Grade 2 water as specified in GB/T 6682.

3.1 Reagents

3.2 Preparation of reagents

3.2.1 Nitric acid solution (5 + 95). MEASURE 50 mL of nitric acid; ADD 950 mL of water;

MIX well.

3.3 Standard

Calcium carbonate (CaCO3, CAS No. 471-34-1). Purity > 99.99 %, or calcium standard

solution at a certain concentration certified by the state and awarded the standard

substance certificate.

3.4 Preparation of standard solutions

3.4.1 Calcium standard stock solution (1000 mg/L). accurately WEIGH 2.4963 g (to

the nearest 0.0001 g) of calcium carbonate; ADD hydrochloric acid solution (1 + 1) to

dissolve; TRANSFER to a 1000 mL volumetric flask; ADD water to the mark; MIX well.

4 Instruments and equipment

NOTE. All glassware and polytetrafluoroethylene digestion inner tank must be soaked in nitric

acid solution (1 + 5) overnight, washed repeatedly with tap water, and finally rinsed with water.

4.1 Atomic absorption spectrometer. with flame atomizer, calcium hollow cathode lamp.

4.4 Adjustable electric furnace.

4.5 Adjustable electric hot plate.

4.6 Pressure digestion tank. with polytetrafluoroethylene digestion inner tank.

4.7 Constant temperature oven.

5 Analysis procedure

5.1 Sample preparation

NOTE. Sample contamination shall be avoided during sampling and sample preparation

processes.

5.2 Sample digestion

5.2.1 Wet digestion

Accurately WEIGH 0.2 g ~ 3 g (to the nearest 0.001 g) of solid sample or accurately

PIPETTE 0.500 mL ~ 5.00 mL of liquid sample in a graduated digestion tube;

5.2.2 Microwave digestion

Accurately WEIGH 0.2 g ~ 3 g (to the nearest 0.001 g) of solid sample or accurately

PIPETTE 0.500 mL ~ 3.00 mL of liquid sample in a microwave digestion tank; ADD 5

mL of nitric acid. DIGEST the sample according to procedure of the microwave

digestion, refer to Annex A for digestion conditions. REMOVE the digestion tank after

cooling; PLACE it on the electric hot plate to get rid of acid to about 1 mL at 140 °C ~

160 °C. After the digestion tank is cool, TRANSFER the digestion solution to a 25 mL

volumetric flask;

5.3 Instrument reference conditions

See Annex B for reference conditions.

5.4 Plotting of standard curve

The calcium standard series solutions are introduced into the flame atomizer according

to the order of the concentration from low to high, the absorbance values are measured.

The standard curve is plotted by taking the concentration of calcium in the standard

series solutions as the abscissa and the corresponding absorbance values as the

ordinate.

6 Expression of analysis results

The content of calcium in the sample is calculated according to equation (1).

7 Precision

The absolute difference between two independent determination results obtained

under repeatability conditions shall not exceed 10 % of the arithmetic mean.

8 Others

When weighing 4 g (or 4 mL) of sample, diluting to the constant volume of 25 mL for

calculation,

9 Principle

Within the proper pH range, calcium forms metal complex with EDTA (disodium

ethylenediaminetetraacetate).

10 Reagents and materials

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

and the water is Grade 3 water as specified in GB/T 6682.

10.1 Reagents

10.1.6 Calcium red indicator (C21O7N2SH14).

10.1.7 Nitric acid (HNO3). excellent regent.

10.1.8 Perchloric acid (HClO4). excellent regent.

10.2 Preparation of reagents

10.2.1 Potassium hydroxide solution (1.25 mol/L). WEIGH 70.13 g of potassium

hydroxide; DILUTE with water to 1000 mL; MIX well.

10.2.6 Hydrochloric acid solution (1 + 1). MEASURE 500 mL of hydrochloric acid; MIX

well with 500 mL of water.

10.3 Standard

Calcium carbonate (CaCO3, CAS No. 471-34-1). with purity > 99.99 %, or calcium

standard solution at a certain concentration certified by the state and awarded the

standard substance certificate.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 14 pages — is available in the English PDF.

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