Determination of triazine herbicides by capillary gas chromatography with large-volume on-column injection

Summary This paper describes a study of the potential of large-volume on-column injection for the determination of triazine herbicides in clean water samples (ground-water). The sensitivity of chromatographic determination has been increased by two orders of magnitude by injection of up to 200 μL of pesticide solutions and nitrogen-phosphorus detection. Analytical characteristics expressed as precision, linear range and limit of detection have been determined, the results indicating adequate analytical performance and the ruggedness of the injection technique. As an application, gas chromatography with large-volume on-column injection and nitrogen-phosphorus detection was combined with off-line liquid-liquid micro-extraction with hexane (1 mL water/1 mL hexane). The procedure was applied to spiked groundwater samples at two concentration levels (1 and 10 μg L⁻¹) with good recoveries (between 81 and 103%, except for deethylatrazine) and repeatability (better than 15% at the 1 μg L⁻¹ level). Limits of detection of the triazine herbicides studied ranged from 0.08 to 0.16 μgL⁻¹.