Determination of 15 Rare Earth Elements in Kaolin by ICP-MS

After the Kaolin sapmle was digested with a mixture of nitric acid, hydrofluoric acid and sulfuric acid, 15 rare earth elements in the sample were determined by ICP-MS with ¹⁰³Rh as internal standard. The MS interference was eliminated with the calibration curves prepared with working solution by using standard substances, and the non MS interference was eliminated by controlling dilution factor. The linearity ranges of 15 elements were 0.20-200 mg·kg^-1, with detection limits in the range of 0.03-0.09 mg·kg^-1. The proposed method was applied to analyze rock standard sbustances, giving the relative error between determined values and certified values in the range of -6.7%-8.3%, RSDs (n=5) in the range of 0.70%-5.9%. RSDs (n=3) of the determined values of 15 elements in real samples were in the range of 3.8%-12%.