1 Scope
This standard specifies the method for limit test of heavy metals in food additives.
This standard is applicable to the limit test of heavy metals in food additives.
2 Principle
In weak acid (pH 3~4) conditions, heavy metal ions in the specimen act with hydrogen sulfide, generating brownish black; compare it with the result generated by the limit test with standard lead solution.
3 Reagents and Materials
Note: unless otherwise specified, the reagents used in this standard are all analytically pure, and the water used is Class I water specified in GB/T 6682.
3.1 Reagents
3.1.1 Nitric acid (HNO3).
3 1.2 Sulfuric acid (H2SO4).
3.1.3 Chlorhydric acid (HCl).
3.1.4 Ammonia (NH3?H2O).
3.1.5 Ammonium acetate (C2H7NO2).
3.1.6 Dihydroxy phalophenone (C2OH14O4).
3.1.7 Hydrogen dioxide (H2O2).
3.1.8 Hydrogen sulfide (H2S).
3.1.9 Perchloric acid (HClO4)
