Conversion of a conventional packed-column gas chromatograph to accommodate megabore columns : I. Evaluation of the system for organophosphorus pesticides

Abstract

A conventional packed-column chromatograph was modified for use with a megabore column using a commercial conversion kit, with the intention of developing a multi-residue method for organophosphorus pesticides. The results indicate that the conversion does not affect the resolving power of the megabore column, since fourteen organophosphorus pesticides could be separated in a single injection. The megabore column in such a system proved to be much more efficient than a packed column in terms of resolution and qualitative reproducibility, and comparable with a similar column in a dedicated chromatograph. However, the conversion did affect the quantitative reproducibility of the system to some degree, as indicated by coefficients of variation between 5 and 27%, although it was determined that the particular nitrogen—phosphorus detector system (filament bead) used in this study was partly responsible for the variation. Nevertheless, calibration curves were obtained down to 0.1 ng per component, and a limit of quantitation of 1.0 ng was established for each component in a sample containing fourteen organophosphorus compounds. The results indicate that the system is sufficiently reproducible to develop a multi-residue method for organophosphorus pesticides in environmental waters.