GB 28308-2012National food safety standard -- Food additive -- Vegetable carbon black (English PDF)

2.1 Chemical name

Carbon

2.2 Molecular formula

2.3 Relative molecular mass

A.1 General

Unless specified otherwise, all reagents used for this Standard are analytically pure reagents and the water is water grade 3 specified in GB/T 6682-2008.Unless specified otherwise, the standard titration solutions used for this Standard and the standard solutions, preparations and products used for the determination of impurities shall be prepared in accordance with GB/T 601, GB/T 602 and GB/T 603.The solutions used in the test refers to aqueous solutions when the solvent is not indicated for the preparation.

A.2 Identification test

A.2.1 Solubility test

Weigh 0.1 g of sample; add 100 mL of water; shake up and allow to stand for 10 min.

The solution shall show no colour.

Weigh 0.1 g of sample; add 100 mL of cyclohexane; shake up and allow to stand for

10 min. The solution shall show no colour.

A.3 Determination of loss on drying

A.3.1 Apparatus

A.3.2 Analytical procedure

Weigh about 2 g of sample, accurate to 0.000 1 g; place in a constant weighing bottle in a constant temperature drying oven at 120°C ± 2°C; dry in the constant drying oven at 120°C ± 2°C for 4 h; take out sample and cool in a desiccator to room temperature.

A.3.3 Calculation of results

Loss on drying is calculated by mass fraction w1; the value is expressed in %; it is calculated in accordance with Formula A.1.

A.4 Determination of carbon content (based on dry basis)

A.4.1 Apparatus

A.5 Determination of ash content

A.5.1 Apparatus

A.5.1.1 Porcelain crucible. 30 mL.

A.5.1.2 High-temperature electric furnace.

A.5.2 Analytical procedure

Weigh about 1 g of sample, accurate to 0.000 1 g; place in a crucible burned to constant weight at 625°C ± 20°C. Place the crucible into a high-temperature electric furnace at temperature not exceeding 300°C; open the crucible cover; increase temperature gradually; ash to constant weight at 625°C ± 20°C.

A.5.3 Ash content is calculated by mass fraction w3; the value is expressed in %; it is calculated in accordance with Formula A.3.

A.6 Determination of alkali soluble colour pigments

A.6.1 Reagents and materials

Sodium hydroxide solution. 1 mol/L.

A.6.2 Analytical procedure

Weigh about 2 g of sample, accurate to 0.000 1 g; place in a 100 mL conical flask; add

20 mL of sodium hydroxide solution; heat slowly to boiling; filter after cooling. The filtrate shall show no colour, i.e. it passes the test.

A.7 Determination of higher aromatic hydrocarbon

A.7.1 Reagents and materials

A.7.2 Apparatus

Continuous extraction apparatus.

A.7.3 Analytical procedure

A.7.3.1 Preparation of quinine sulfate-sulfuric acid reference solution

Weigh about 0.1 g of quinine sulfate, accurate to 0.000 1g; add 100 mL of sulfuric acid solution; transfer to a 1 000 mL volumetric flask after dissolving; add sulfuric acid solution to the scale; shake up. Absorb 1 mL of the solution to transfer to a 1 000 mL volumetric flask; add sulfuric acid solution to the scale and shake up as standby.

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