Determination of triazine herbicides by capillary liquid chromatography with on-column focusing and temperature gradient

The combination of capillary liquid chromatography, temperature gradient and on-column focusing with large injection volumes offers a powerful tool for the determination of very low concentrations of triazines and their degradation products when very polar degradation products are present. A temperature gradient from subambient temperatures up to 70°C allows separation of eight triazines in 24min. The focusing step makes it possible to increase 50 times the sample volume that can be injected into a capillary column. Detection limits (3 ×noise) are improved by a factor between 50 and 125 to 9ngl-1 for hydroxyatrazine and 45ngl-1 for atrazine. The chromatographic method, combined with solid phase extraction, was applied to the determination of eight triazines in ground water.