GB 1886.333-2021National food safety standard - Food additives - Calcium dihydrogen phosphate (English PDF)

2.1 Molecular formula

Anhydrous calcium dihydrogen phosphate: Ca(H2PO4)2 Calcium dihydrogen phosphate monohydrate: Ca(H2PO4)2·H2O

2.2 Relative molecular mass

Anhydrous calcium dihydrogen phosphate: 234.05 (as per 2018 internal relative atomic mass)

Calcium dihydrogen phosphate monohydrate: 252.07 (as per 2018 internal relative atomic mass)

3.1 Sensory requirements

The sensory requirements shall comply with the provisions of Table 1.

3.2 Physicochemical index

A.1 General provisions

If no other requirements are specified, all the reagents and water used in this Standard refer to the analytical reagents and Class-III water specified in GB/T 6682. If no other requirements are specified, all the standard solution used in the test, standard solution for determining the impurity, preparation and product shall be prepared according to the provisions of GB/T 601, GB/T 602, GB/T 603. The solution used in the test refers to the aqueous solution when the solvent is not specified.

A.2 Identification test

A.2.1 Reagents and materials

A.2.1.1 Nitric acid solution: 1+1.

A.2.1.2 Hydrochloric acid solution: 1+3.

A.2.1.3 Ammonium oxalate solution: 35g/L.

A.2.1.4 Ammonium molybdate solution: 60g/L, take 6g of ammonium molybdate [(NH4)6MO7O24·4H2O] and dissolve it in 50mL of water, slowly add 50mL of nitric acid solution while stirring, and store in a brown reagent bottle.

A.2.2 Identification method

A.2.2.1 Identification of calcium ions

Take about 0.1g of specimen; add 2mL of hydrochloric acid solution, 8mL of water; heat to 40°C ~ 50°C; add 5mL of ammonium oxalate solution; and a white precipitate is produced.

A.2.2.2 Identification of phosphate radical

Take about 0.1g of specimen; titrate nitric acid solution to dissolve the specimen; then excess 1mL of nitric acid solution; heat to 40°C ~ 50°C; add 10mL of ammonium molybdate solution; and produce yellow precipitate. […]

A.3.2.2 Reagents and materials

A.3.2.2.1 Hydrochloric acid solution: 1+1.

A.3.2.2.2 Ammonia-ammonium chloride buffer solution (A): pH~10.

A.3.2.2.3 Ethylenediaminetetraacetic acid disodium salt (EDTA) standard titration solution: c(EDTA)=0.05mol/L.

A.3.2.2.4 Acid chrome blue K-naphthol green B mixed indicator liquid (KB indicator liquid).

A.3.2.2.5 Zinc sulfate standard titration solution: c(ZnSO4·7H2O) = 0.05mol/L.

Preparation: Take 15g of zinc sulfate; add water to dissolve' dilute to 1000mL with water; and shake well.

Calibration: Pipette 25.00mL of prepared zinc sulfate standard titration solution; place it in a conical flask; add 10mL of ammonia-ammonium chloride buffer solution (A) and 75mL of water; add about 0.02g of chrome black T indicator. Use 0.05mol/L ethylenediaminetetraacetic acid disodium salt (EDTA) standard titration solution to titrate until the solution turns from purple to pure blue; and it does not fade for 30s, which is the end point. At the same time, a blank test is carried out.

Except for the blank test without adding the specimen, other operations and the types and amounts of the added reagents (except the standard titration solution) are the same as the determination test.

The concentration of zinc sulfate standard titration solution c2, the unit is mol/L, shall be calculated according to Formula (A.2).

Where:

V2 - volume of ethylenediaminetetraacetic acid disodium salt (EDTA) standard titration solution consumed for titration, in mL;

V3 - volume of ethylenediaminetetraacetic acid disodium salt (EDTA) standard titration solution consumed by blank test, in mL;

25 - volume of pipetted specimen solution, in mL;

250 - constant volume of specimen solution, in mL.

The test results are based on the arithmetic mean of the parallel determination results.

The absolute difference between two independent determination results obtained under repeatability conditions is no more than 0.2%.

A.4 Determination of loss on drying

A.4.1 Apparatus

A.4.1.1 Weighing bottle: phi50mm×30mm

A.4.1.2 Electric heating constant temperature drying oven

The temperature control range is 60°C±2°C.

A.4.2 Analysis procedures

Use a weighing bottle that has been dried at 60°C±2°C for 3h; weigh about 1.5g of specimen (monohydrate), accurate to 0.0002g; and place it in an Electric heating constant temperature drying oven at 60°C±2°C. Dry for 3h, take out and cool to room temperature, and weigh it.

A.4.3 Calculation of results

The mass fraction w2 of loss on drying is calculated according to Formula (A.4).

Where: m3 - mass of specimen and weighing bottle before drying, in g; m4 - mass of specimen and weighing bottle after drying, in g; m5 - mass of specimen, in g.

The test results are based on the arithmetic mean of the parallel determination results.

The absolute difference between two independent determination results obtained under repeatability conditions is no more than 0.1%.

A.5 Determination of loss on ignition

A.5.1 Apparatus

A.5.1.1 Porcelain crucible: 30mL

A.7 Determination of carbonate

A.7.1 Reagents and materials

Hydrochloric acid.

A.7.2 Analysis procedures

Weigh 2.0g of the specimen, accurate to 0.1g; place it in a 50mL conical flask; add 6mL of water to boil; titrate 2mL of hydrochloric acid after cooling. If the sample solution does not produce bubbles, it shall be regarded as passing the test.

A.8 Determination of free acid and its side salt

A.8.1 Reagents and materials

A.8.1.1 Sodium hydroxide solution: 1mol/L.

A.8.1.2 Methyl orange indicator solution: 1g/L.

A.8.2 Analysis procedures

Weigh 1.0g of specimen, accurate to 0.1g; place it in a mortar; add 3 mL of water to grind; transfer all to a 250 mL beaker. Add 100 mL of water to shake; add 1 drop of methyl orange indicator solution; and add 1 mL of sodium hydroxide solution. If the sample solution turns yellow, it shall be regarded as passing the test.

A.9 Determination of lead (Pb)

The measurement is carried out according to the method specified in Method-I of GB 5009.75-2014 or in Method-II, III, IV of GB 5009.12-2017; and the water used in the test is the Class-II water specified in GB/T 6682.

A.10 Determination of Arsenic (As)

The measurement is carried out according to the method specified in GB 5009.76 or […]