Determination of polar pesticides in ground water using liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization.

A method is described for determination of pesticides in ground water by liquid chromatography combined with mass spectrometry (LC-MS) using atmospheric pressure chemical ionization (APCI). The study demonstrates the sensitivity of the technique, with detection limits for water samples of about 0.001-0.005 microgram/l, corresponding to 50-300 pg injected. Performance data for the method such as recovery, precision and linearity are also reported. It is illustrated that the technique is applicable for many different types of pesticide structures, such as triazines, phenylurea herbicides, acetanilides, organophosphorus insecticides, etc. Twelve different pesticides and pesticide degradation products are included in the study. The optimization of inlet conditions with respect to sheath gas pressure, vaporizer temperature, capillary temperature and corona current is reported. Applicability of the method for analysis of "real-world" ground water samples is demonstrated.