Determination of trace elements in silicon powder using slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

The determination of B, Al, P, Fe, Ni, Cu, Zn, Cd and Pb in silicon powder by ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) using citric acid as the modifier was investigated. The influences of instrument operating conditions and slurry preparation on the ion signals were studied. A relatively low vaporization temperature of 1900 degrees C was used, which separated the analyte from the major matrix components that not only improved ion signals significantly but also alleviated the spectral interferences caused by (SiSi+)-Si-28-Si-29, (SiOO+)-Si-28-O-16-O-16, (SiOO+)-Si-28-O-17-O-18 and (ArSi+)-Ar-38-Si-28 on Fe-57(+), Ni-60(+), Cu-63(+) and Zn-66(+) determinations. The method has been applied to determine B, Al, P, Fe, Ni, Cu, Zn, Cd and Pb in a 99.999% pure silicon powder sample and four solar grade silicon powder samples using standard addition calibration methods. The concentrations that are in mg g(-1) to sub mg g(-1) levels were in good agreement with those of digested samples analyzed by pneumatic nebulization membrane desolvation ICP-MS. The precision between sample replicates was better than 9% with USS-ETV-ICP-MS technique. The method detection limit estimated from standard addition curves was about 8, 7, 9, 50, 9, 3, 7, 1 and 0.4 ng g(-1) for B, Al, P, Fe, Ni, Cu, Zn, Cd and Pb, respectively, in original silicon samples.