A contribution to the analysis of microamounts of biological samples using a combination of graphite furnace and microwave induced plasma atomic emission spectroscopy

Abstract

The use of a commercial graphite furnace combined with a TM 110 microwave cavity for the multielement analysis of small-volume liquid samples by microwave-induced plasma atomic emission spectroscopy is described. Sample aliquots of 5–50 μl are dried at 100°C and subsequently vaporized by heating up to 2400°C. When the dry vapour cloud is evoluted into a 40 W argon microwave plasma with an argon carrier gas flow of 4.51/min, detection limits for Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Tl and Zn range from 1–50 ng ml . Atomic lines are predominant. In routine analysis the analytical performance of the system is judged by the analysis times of 2–3 min per sample, the absence of memory effects and relative standard deviations in the range of 0.02–6.07. The analytical precision is improved by a factor of 2 by using a reference line. As varying alkaline contents, organics and various anions evoke matrix effects, the analysis of real samples requires the use of standard addition methods. Analysis results for Cd, Cu, Mn, Pb and Zn in NBS orchard leaves and bovine liver agree well with certified values. Direct determinations of Fe, Cu and Zn in 50 μl serum samples are possible when applying adequate thermal decomposition of samples in the furnace.