Coupled gas chromatography–atomic absorption spectrometry using semi-enclosed tubular atomizers: theoretical analysis of detector performance characteristics

Abstract

For the determination of specific organometallic compounds in various environmental samples, coupled gas chromatography–atomic absorption spectrometry (GC–AAS) has proved to be a useful instrumental combination. However, to enable the optimum dimensions and operating conditions of the atomizer to be identified requires consideration of the theoretical aspects of GC–AAS detector performance. In this work, expressions are derived to describe the relative values of the detector sensitivity (peak height), and chromatographic efficiency and resolution in terms of the ratio between the residence time of the analyte in the atomizer and the standard deviation of the (assumed) Gaussian peak eluting from the GC system (τ_R/σ_G). The greatest detector sensitivity is obtained at high τ_R/σ_G values, but at the expense of degraded separation capabilities. Recommendations are given for the design of GC–AAS systems providing the best possible performance characteristics. A detector response model is also presented for predicting characteristic mass values (peak height and peak area) provided by GC–AAS systems and verified using literature data and experimental results.