GB 5009.76-2014National food safety standard - Determination of arsenic in food Additives (English PDF)

3.1 Reagents

3.1.1 Nitric acid (HNO3). excellent grade pure.

3.1.11 Pyridine (C5H5N).

3.1.12 Silver diethyldithiocarbamate (C5H10AgNS2).

3.1.13 Triethanolamine (C6H15NO3).

3.1.14 Ethanol (C2H5OH).

3.1.15 Phenolphthalein (C2OH14O4).

3.1.16 Lead acetate (C4H6O4Pb - H2O).

3.2 Reagent preparation

3.2.1 Sulfuric acid solution (1 + 1). MEASURE 100 mL of sulfuric acid; slowly

ADD it into 100 mL of water; MIX it uniformly; COOL it down before use.

3.2.2 Sulfuric acid solution (1 mol/L). MEASURE 28 mL of sulfuric acid; slowly

ADD it into water; USE water to dilute it to 500 mL.

3.2.3 Hydrochloric acid solution (1 + 1). MEASURE 100 mL of hydrochloric

acid; slowly ADD it into 100 mL of water; MIX it uniformly; COOL it down before use.

3.2.10 Phenolphthalein ethanol solution (10 g/L). WEIGH 1.0 g of phenolphthalein; DISSOLVE it into 100 mL of ethanol solution.

3.2.11 Lead acetate solution (100 g/L). WEIGH 10 g of lead acetate; USE

water to dissolve it and MAKE its volume reach to 100 mL.

3.3 Standard substance

Arsenic trioxide (As2O3) standard substance. the purity is 99.99% OR the standard substance certified and awarded the standard substance certificate by the state.

3.4 Standard solution preparation

3.5 Materials

Lead acetate cotton. DIP the absorbent cotton into the lead acetate solution (10%) for 2 h; TAKE it out and DRY it naturally.

5.1 Preparation of inorganic samples

The "sample treatment" of the inorganic sample may be carried out in accordance with the method as specified in the relevant standards.

5.2 Preparation of organic samples

The "sample treatment" of organic sample shall, in addition to the requirements of relevant standards, generally follow the methods below.

6.1 Selection of absorption solution

The absorption solution A or the absorption solution B can be selected in accordance with the demands of analysis. During the determination process, the same absorption solution is applied to the sample, blank and standard solution.

6.2 Limited amount test

6.2.1 PIPETTE a certain amount of sample solution and arsenic standard use

solution (arsenic content of not less than 5 µg), respectively, into the arsenic generation bottle A; ADD sulfuric acid to a total of 5 mL; ADD 50 mL of water.

6.2.2 In each bottle as mentioned in 6.2.1, ADD 3 mL of potassium iodide solution; MIX it uniformly; LET it stand for 5 min.

6.2.3 USE the visual colorimetric method or USE the 1 cm cuvette to determine the absorbance of the absorption solution at the wavelength 515 nm (absorption solution A) or the wavelength 540 nm (absorption solution B).

6.3 Quantitative determination

6.3.1 PIPETTE 25 mL (or the appropriate amount of) sample solution and the same amount of reagent blank solution; respectively PLACE it into the arsenic generation bottle A; ADD sulfuric acid to a total of 5 mL; ADD 50 mL of water.

6.3.3 ADD 3 mL of potassium iodide solution into the sample solution, reagent

blank solution and arsenic standard solution; MIX it uniformly; LET it stand for 5 min; then respectively ADD 1 mL of stannous chloride solution; MIX it uniformly; LET it stand for 15 min; respectively ADD 5 g arsenic-free metal zinc;

immediately PLUG the air duct B which is equipped with the lead acetate cotton lead, to make the tip of the air duct B insert into the absorption tube C which contains 5.0 mL of absorption solution A or absorption solution B;

10.1 Reagents

10.1.10 Hydrogen peroxide (H2O2).

10.2 Reagent preparation

10.2.1 Sodium hydroxide solution (2 g/L). WEIGH 2.0 g of sodium hydroxide;

DISSOLVE it into 1000 mL of water; MIX it uniformly.

10.2.2 Sodium borohydride solution (10 g/L). WEIGH 10.0 g of sodium

borohydride; DISSOLVE it into 1000 mL of sodium hydroxide solution; MIX it uniformly. PREPARE it before use (it may also weigh 14 g of potassium borohydride to substitute sodium borohydride).

10.3 Standard substance

Arsenic trioxide (As2O3) standard substance. the purity is 99.99% OR the standard substance certified and awarded the standard substance certificate by the state.

10.4 Standard solution preparation