Development and Application of the Detector-Response-Ratio Method of Identification for a Dual-Detection System. Application of GC with Electron-Capture and Nitrogen–Phosphorus Detection to the Determination of Pesticides in Aqueous Matrices

Abstract

Dual detection has already been used to analyse organic contaminants in several matrices and the potential use of this technique for compound identification using the detector-response ratio (DRR) for two detectors has been reported. In this study DRR was redefined in terms of analyte concentration. The ratio was applied to compounds with both positive and negative responses fitting linear or logarithmic calibration plots. Use of DRR has been evaluated for pesticides of several chemical classes (organochlorine, organophosphorus, triazine, and thiocarbamate) and for an organophosphate ester, in aqueous matrices, using electron-capture and nitrogen–phosphorus detection. A limit of confirmation (LOC) was defined as the minimum concentration required for identification of a compound by use of the DRR. The identification results obtained were confirmed by GC–MS.