A COMPARATIVE-STUDY OF 3 MICROWAVE-INDUCED PLASMA SOURCES FOR ATOMIC-EMISSION SPECTROMETRY .2. EVALUATION OF THEIR ATOMIZATION EXCITATION CAPABILITIES FOR CHLORINATED HYDROCARBONS

A comparative analytical survey of the performance of three different helium microwave-induced plasmas (MIP) for atomic emission spectrometry (AES) has been performed using chlorinated hydrocarbons of growing molecular complexity as models. The cavity structures investigated were a Beenakker cavity, a surfatron and a microwave plasma torch (MPT). Detection limits and linear dynamic ranges for Cl and C, capabilities to obtain element ratio determinations (Cl/C ratios), and tolerance to organic solvents were tested for the different MIP cavities. The effect of O-2 scavenger gas in the surfatron to eliminate carbon deposits was also investigated. Results demonstrated that differences in detection limits (DL) observed for the same element in the three cavities were no higher than 2-3 times. The most sensitive He-MIP source proved to be the Beenakker cavity (with DL of 0.05 ng ml-1 for C and 0.5 ng ml-1 for Cl). The MPT source showed its superiority to withstand high levels of organic compounds and was also the structure that provided better correlation between the theoretical and the experimental element ratios obtained for high hydrocarbon concentrations.