CONTINUOUS-WAVE DIODE-LASER TOTAL SOLID SAMPLE VAPORIZATION FOR BIOLOGICAL SAMPLE ANALYSIS - LEAD IN BOVINE LIVER

The potential of a 930 nm, 50 W continuous wave diode laser array as a n efficient and compact solid sample vaporization tool was investigate d. It was found that the power density of the focused laser output was not sufficient for ablation of metals, but vaporization of dry bovine liver powder was feasible. For convenience, a graphite furnace atomic absorption spectrometer was utilized to test the analytical performan ce of the setup via furnace impaction/deposition. The direct depositio n of the vaporized materials onto the inner wall of a graphite tube wi thout a transfer tube was shown to have better precision than depositi on in a hot furnace through a transfer tube. Theoretical calculations and the experimental relationship between gas flow rate and particle c ollection efficiency are reported. Experimental data obtained with two types of ablation cells, straight through and tangential flow, indica ted that the flow pattern inside the cell did not play a major role in terms of analytical performance. Aqueous standard calibration with a matrix modifier was found to be-satisfactory. Determination of lead in bovine liver (SRM 1577a) was performed accurately with the diode lase r vaporization-deposition setup. A lead mass detection limit of about 0.1 ng was achieved. (C) 1996 Academic Press, Inc.