Evaluating the applicability of a two-dimensional liquid chromatography system for a pesticide multi-screening method

In this study, a fully automated two-dimensional liquid chromatography system was evaluated for pesticide analysis. The first dimension was a hydrophilic interaction liquid chromatography column for matrix separation. The analytes were collected on a trap column and transferred to the second dimension with a reversed phase column. This separation system was coupled to a quadrupole time-of-flight mass spectrometer. Investigations were started to elucidate, whether this system is useful for screening purposes. Therefore, analytes with different masses, pK_a and log K_ow values were chosen. The aim was to test, if broadening the scope of this method, without a time-intensive adjustment of the valve switching times is possible. All in all, the limits of the system were determined. It is important that the analytes elute from the hydrophilic interaction liquid chromatography column within a small window. It could be deduced that the window within which the analytes elute expanded too far with the chosen analytes. Therefore, optimization with different buffers, columns, column temperatures, and flow rates was started to minimise the window. Furthermore, differences in the analytes' elution behavior during hydrophilic interaction liquid chromatography separation were elucidated.