Direct solid sampling in capacitively coupled microwave plasma atomic emission spectrometry

Abstract

A capacitively coupled microwave plasma operating in the range between 500 and 700 W is used as an excitation source for the analysis of solid samples. National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) Tomato Leaves (SRM 1573a) and Coal Fly Ash (SRM 1633a) are used for the evaluation of the technique. The system contains a graphite electrode–cup in which the solid sample is deposited. Heating of the electrode–cup vaporizes the analyte into the plasma for atomic emission spectrometry. The detection limits (defined as 3σ of the background) for Mn, Ca, Mg, Zn, Cu, As, Rb and Pb in Coal Fly Ash, and Cd, Fe, Cu, Zn, Zn, Sr, Rb, Mg and Pb in Tomato Leaves were determined. The plasma gas used in this study was 20% nitrogen and 80% helium.