Direct Micro determination of Mercury in Color Additives by the Photometric-Mercury Vapor Procedure

Abstract

Abstract A direct method has been developed for the determination of submicrogram amounts of mercury in inorganic and organic color additives. Samples are pyrolyzed at 650°C, generating mercury vapor from the mercury compounds present in the sample. The pyrolysate is passed over heated copper oxide and swept through a series of traps that remove interfering substances. The mercury content of the gas stream is determined with a commercially available mercury vapor meter. The method requires no pretreatment of the sample, such as digestion and isolation of mercury. Amounts of mercury as low as 0.01 μg can be detected. Samples as large as 25 mg (organic colors) or 250 mg (inorganic colors) may be used. Mercury at a concentration of 0.50 ppm in organic colors and 0.05 ppm in inorganic colors can be determined to within ± 2 0 % . About 5 minutes is required per analysis. The method is not suitable for the determination of mercury in samples containing organically bound iodine.