ELECTROTHERMAL VAPORIZATION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC DETECTION OF AS, SB, SE, BI AND SN FOLLOWING PRECONCENTRATION BY IN-SITU COLLECTION OF THEIR HYDRIDES

Volatile hydrides of As, Se, Sb, Sn and Bi were generated from aqueous sample solutions using a tetrahydroborate reductant. The gaseous analytes were transferred to the inner wall of an electrothermal vaporizer (graphite furnace) and preconcentrated on a 1.25 mu g thin-film of reduced palladium at 400 degrees C. The furnace comprised the sample introduction unit of an inductively coupled plasma mass spectrometric detection system. Absolute limits of detection (3 sigma(B)) were 2.9, 3.3, 54, 5 and 1980 pg for As, Sb, Sn, Bi and Se, respectively. System efficiency for the generation and sequestration of the hydrides averaged, with the exception of Se, better than 75%. Multielement determinations of As, Se and Bi were possible using the same experimental conditions, those for Sn and Sb were accomplished in a separate run. The efficacy of this analytical approach was verified by the analysis of several marine reference materials using simple calibration standards prepared in the same manner as the samples. Good agreement with certified values was achieved for As, Sn, Sb and Se; no reference materials were available for assessment of accuracy in the case of Bi.