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GB 5009.91-2017National food safety standard - Determination of potassium and sodium in foods (English PDF)

食品安全国家标准食品中钾、钠的测定

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Issued by

National Health and Family Planning Commission of the PRC

Level / Type

National · Mandatory

Issue date

April 6, 2017

Implementation date

October 6, 2017

Scope

GB 5009.91-2017 is the English-translated version of 食品安全国家标准食品中钾、钠的测定.

GB 5009.91-2017 — This standard specifies four methods for the determination of potassium and sodium in food. the flame atomic absorption spectrometry, the flame atomic emission spectrometry, the inductively coupled plasma emission spectroscopy, AND the inductively coupled plasma mass spectrometry.

This standard applies to the determination of potassium and sodium in food. Method I. Flame atomic absorption spectrometry

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Document preview — GB 5009.91-2017

National Standard of the People's Republic of China

Issued by: National Health and Family Planning Commission of the PRC

Foreword...3
1 Scope...4
2 Principle...4
3 Reagents and materials...4
4 Instruments and equipment...6
5 Analytical procedures...6
6 Expression of analytical results...9
7 Precision...9
8 Others...9
9 Principles...10
10 Reagents and materials...10
11 Instruments and equipment...11
12 Analytical procedures...12
13 Expression of analytical results...12
14 Precision...13
15 Others...13
Appendix A Sample determination reference condition...14

Foreword

This standard replaces the potassium and sodium determination part in GB/T

5009.91-2003 "Determination of potassium and sodium in foods", GB/T

15402-1994 "Fruits, vegetables and derived products – determination of

sodium and potassium", NY 82.18-1988 "Determination of potassium and

sodium in fruit juice", 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 18932.11-2002 "Method for determination of potassium,

phosphorus, iron, calcium, zinc, aluminum, sodium, magnesium, boron,

manganese, copper, barium, titanium, vanadium, nickel, cobalt and chromium

in honey - Inductively coupled plasma atomic emission spectrometry (ICP-AES

method", GB/T 18932.12-2002 "Method for determination of potassium,

sodium, calcium, magnesium, zinc, iron, copper, manganese, chromium, lead

and cadmium contents in honey - Atomic absorption spectrometry", AND NY/T

1653-2008 "Determination for mineral elements in vegetables, fruits, and

derived products by ICP-AES method".

As compared with the above standards, the main changes are as follows.

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

Determination of potassium and sodium in foods";

- MODIFY the flame atomic absorption spectrometry method as the first

method, the flame atomic emission spectrometry method as the second

method, the inductively coupled plasma emission spectroscopy method

as the third method, AND the inductively coupled plasma mass

spectrometry as the fourth method;

- MODIFY some part of the sample preparation;

- MODIFY some part of the sample digestion;

- INCREASE the method detection limit and quantitative limit;

- ADD appendix.

National food safety standard

Determination of potassium and sodium in foods

1 Scope

This standard specifies four methods for the determination of potassium and

sodium in food. the flame atomic absorption spectrometry, the flame atomic

emission spectrometry, the inductively coupled plasma emission spectroscopy,

AND the inductively coupled plasma mass spectrometry.

This standard applies to the determination of potassium and sodium in food.

Method I. Flame atomic absorption spectrometry

2 Principle

After digestion, the sample is injected into the atomic absorption spectrometer.

After the flame atomization, the potassium and sodium respectively absorb the

766.5 nm and 589.0 nm resonance line. AND within a concentration range, its

absorption value is proportional to the contents of potassium and sodium, AND

it is quantified through comparison with standard series.

3 Reagents and materials

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

grade pure, AND the water is level II water as specified in GB/T 6682.

3.1 Reagents

3.2 Reagent preparation

3.3 Standard substance

3.3.1 Potassium chloride standard substance (KCl). its purity is greater than

99.99%.

3.3.2 Sodium chloride standard substance (NaCl). its purity is greater than

99.99%.

3.4 Preparation of standard solution

3.4.1 Potassium and sodium standard stock solution (1000 mg/L). PLACE the

potassium chloride or sodium chloride in the oven at 110 °C ~ 120 °C to dry it

for 2 h. Accurately WEIGH 1.9068 g of potassium chloride or 2.5421 g of

sodium chloride;

3.4.2 Potassium and sodium standard working solution (100 mg/L). accurately

PIPETTE 10.0 mL of potassium or sodium standard stock solution in a 100 mL

volumetric flask; USE water to dilute it to the mark; STORE it in a polyethylene

bottle; PRESERVE it at 4 °C.

3.4.3 Potassium and sodium standard series working solution. accurately

PIPETTE 0 mL, 0.1 mL, 0.5 mL, 1.0 mL, 2.0 mL, and 4.0 mL of potassium

standard working solution in 100 mL volumetric flask; ADD 4 mL of cesium

chloride solution; USE water to make its volume reach to the mark;

4 Instruments and equipment

4.1 Atomic absorption spectrometer, with flame atomizer and potassium,

sodium hollow cathode lamp.

4.2 Analytical balance. sensitivity of 0.1 mg and 1.0 mg.

4.5 Muffle furnace.

4.6 Adjustable temperature control heating plate.

4.7 Adjustable temperature control electric furnace.

4.8 Microwave digestion instrument, with a polytetrafluoroethylene digestion

internal tank.

5 Analytical procedures

5.1 Preparation of sample

5.1.1 Solid samples

5.1.1.1 Dry sample

As for the beans, cereals, fungi, tea, dried fruit, baked goods and other low

water content samples, TAKE the edible part; USE high-speed grinder to crush

it uniformly if necessary; AND as for the solid dairy products, protein powder,

flour, and other uniform powdery sample, SHAKE it uniformly.

5.1.3 Semi-solid samples

STIR it uniformly.

5.2 Sample digestion

5.2.1 Microwave digestion method

WEIGH 0.2 g ~ 0.5 g (accurate to 0.001 g) of sample; PLACE it into the

microwave digestion tank; as for the samples containing ethanol or carbon

dioxide, PLACE it on the heating plate to heat it at low temperature to remove

ethanol or carbon dioxide; ADD 5 mL ~ 10 mL of nitric acid; COVER and

PLACE it for 1 h or overnight; TIGHTEN the external tank; PLACE it in the

microwave digestion device for digestion (the digestion conditions are as

shown in Table A.1). After cooling it, TAKE out the internal tank; PLACE it in an

adjustable temperature control electric furnace; REMOVE acid at 120 °C ~

140 °C to make it almost dry; USE water to make its volume reach to 25 mL or

50 mL; MIX it uniformly to prepare for use; and meanwhile MAKE blank test.

5.2.4 Dry digestion method

WEIGH 0.5 g ~ 5 g (accurate to 0.001 g) of sample in the crucible; MAKE it

subject to carbonization in the electric furnace at small fire to make it

smokeless; PLACE it into the 525 °C ± 25 °C muffle furnace for ashing for 5 h ~

8 h; COOL it. If there is black carbon particles due to incomplete ashing, COOL

it and ADD a small amount of nitric acid to wet it;

5.3 Instrument reference conditions

OPTIMIZE the instrument to the best condition, AND the main conditions of the

instrument are as shown in Table A.2.

5.4 Production of standard curve

Respectively INJECT the potassium and sodium standard series working

solution into the atomic absorption spectrometer;

5.5 Determination of sample solution

In accordance with the content of the element under determination in the

sample solution, USE water to dilute the sample solution to the appropriate

concentration if necessary; and ADD a certain amount of cesium chloride

solution into the blank solution and the sample final determination solution, to

make the concentration of cesium chloride reach to 0.2 %.

6 Expression of analytical results

The potassium and sodium contents in the sample are calculated in

accordance with the formula (1).

7 Precision

The absolute difference between the two independent determinations obtained

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

8 Others

If the sampling amount is 0.5 g and its volume is made to 25 mL, the detection

limit of sodium is 0.2 mg/100 g AND the quantification limit is 0.5 mg/100 g;

9 Principles

After the sample is subjected to digestion, it is injected into the flame

photometer or atomic absorption spectrometer; AND after the flame

atomization, the emission intensity of potassium and sodium is determined

respectively.

......

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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.

Referenced standards

Cited by

LS/T 3268-2020Moringa oleifera leaf powder

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