GB 1886.330-2021National food safety standard - Food additives - Ammonium dihydrogen phosphate (English PDF)

2.1 Molecular formula

NH4H2PO4

2.2 Relative molecular mass

115.02 (according to the international relative atomic mass in 2018)

3.1 Sensory requirements

Sensory requirements shall be in accordance with Table 1.

3.2 Physical and chemical indicators

Physical and chemical indicators shall be in accordance with Table 2.

A.1 General provisions

The reagents and water that are used in this Standard, when no other requirements are specified, refer to analytical reagents and grade-III water which is specified in GB/T 6682. The standard titration solution, the standard solutions, preparations and products for impurity determination, which are used in the test, are all prepared in accordance with the provisions of GB/T 601, GB/T 602, and GB/T 603, when no other requirements are specified. The used solution, if not indicated which solvent is used, refers to aqueous solution.

A.2 Identification test

A.2.1 Reagents and materials

A.2.1.1 Nitric acid solution: 1+8.

A.2.1.2 Ammonia solution: 1+1.

A.2.1.3 Sodium hydroxide solution: 40 g/L.

A.2.1.4 Silver nitrate solution: 17 g/L.

A.2.1.5 Litmus red test paper.

A.2.2 Identification method

A.2.2.1 Identification of phosphate ion

Weigh 1.0 g of the sample; dissolve it in 20 mL of water; add silver nitrate solution, to produce a yellow precipitate. This precipitate is soluble in ammonia solution or nitric acid solution.

A.2.2.2 Identification of ammonium ion

A.3

Where:

V1 - the volume of sodium hydroxide standard titration solution that is consumed by the titration sample solution, in milliliters (mL);

V2 - the volume of sodium hydroxide standard titration solution that is consumed by the titration blank sample solution, in milliliters (mL);

c - the concentration of the sodium hydroxide standard titration solution, in moles per liter (mol/L);

M - the molar mass of ammonium dihydrogen phosphate (1/2NH4H2PO4), in grams per mole (g/moL) (M = 57.51);

m - sample mass, in grams (g).

1 000 - conversion factor.

The test result is based on the arithmetic mean of the parallel determination results. The absolute difference between two independent determination results that are obtained under repeatability conditions is not more than 0.3%.

A.4 Determination of pH (10 g/L aqueous solution)

A.4.1 Reagents and materials

Carbon dioxide-free water.

A.4.2 Instruments and apparatuses

Acidity meter: resolution of 0.01 pH, equipped with glass electrode and saturated calomel electrode (or composite electrode).

A.4.3 Analysis steps

Weigh 1.00 g ± 0.01 g of the sample; place it in a 100 mL beaker; use carbon dioxide-free water to dissolve; transfer it into a 100 mL volumetric flask; use carbon dioxide-free water to dilute to the mark; shake well. Pour into a dry beaker; use a calibrated acidity meter to measure the pH of the sample solution.

The test result is based on the arithmetic mean of the parallel determination results. The absolute difference between two independent determination results that are obtained under repeatability conditions is not more than 0.1.

A.5 Determination of lead (Pb)