Study of a toroidal argon MIP and a cylindrical helium MIP for atomic emission spectrometry—II: Combination with graphite furnace vaporization and use for analysis of biological samples

Abstract

The capabilities of a toroidal argon and a diffuse helium microwave induced plasma (MIP) operated in a TM 010 resonator and in combination with electrothermal vaporization have been studied for atomic emission spectrometry (AES). The 75 W toroidal MIP has been found to improve the power of detection with respect to the filament argon MIP by a factor of 3–10. The detection limits using 50 μl solution aliquots for a large series of elements are between 0.1 and 100 ng ml . With a diffuse helium MIP in combination with graphite furnace vaporization the detection limit for P is 10 ng ml and for Pb 1 ng ml . In the toroidal argon MIP, matrix effects due to alkali elements occur already at concentrations of 10 μg ml of Na and could not be eliminated satisfactorily by the use of NH 4NO 3. In. the helium MIP, also volatilization interferences in the case of Ca and P were found. After separation of the alkali elements by sorption of the trace elements as hexamethylene-dithiocarbamates (HMDC) on acetylated cellulose, MIP-AES with the toroidal argon MIP coupled to electrothermal vaporization has been found to be suitable for multielement determinations in biological samples, subsequent to wet chemical sample decomposition in closed PTFE (Teflon) vessels. This is demonstrated by the determination of Fe, Cu and Zn in the NBS standard reference materials of bovine liver, orchard leaves and tomato leaves.