Determination of Lead, Arsenic, Mercury, Cadmium in 3D Hard Gold Jewelry by ICP-AES with Microwave Digestion

The sample (about 0.1 g) was added into 6 mL of a mixture of hydrochloric acid and nirtic acid (3+1) for microwave digestion according to digestion program. After the digestion was completed, the solution was heated at 80 ℃ to remove nitrogen oxide, cooled to room temperature, and made up to 50 mL with water. The contents of lead, arsenic, mercury and cadmium in the solution was determined by inductively coupled plasma atomic emission spectrometry. Linear relationships were found between emission intensity and mass concentration of the 4 elements in the same range of 0.10-10.0 mg·L^-1, with detection limits (3s) in the range of 2.0-8.0 mg·kg^-1. Values of recovery obtained by standard addition method were in the range of 91.0%-103%. The proposed method was applied to determination of the 4 elements in 21 batches of hard gold jewelry samples, giving results in consistency with those obtained by inductively coupled plasma mass spectrometry, and RSDs (n=6) were less than 3.0%.