This standard specifies the limit test and quantitative test methods to determine the lead in food additives.
This standard is applicable to the limit test and quantitative test on lead in food additives.
Method I Diphenyl Thiocarbazone (Dithizone) Colorimetry
2 Principle
Treat the sample by adding diammonium hydrogen citrate, potassium cyanide and hydroxylamine hydrochloride, etc., to eliminate the interference of ions such as iron, copper and zinc. At pH 8.5~9.0, the lead ion reacts with diphenyl thiocarbazone (dithizone) to generate red complex which is extracted with trichloromethane. Carry out limit test or quantitative test and compare with the standard series.
3 Reagents and Materials
Note: unless otherwise specified, the reagents used in this method are analytically pure, and the water is Grade 1 water specified in GB/T 6682.
