Analytical quality parameters of high performance liquid chromatography with diode-array detection method for multiresidue determination of pesticides.

A study was done to establish the linearity, analytical sensitivity, limit of detection, limit of identification and precision of a method for the simultaneous detrmination of thirteen pesticides belonging to different chemical classes: methyl-carbamates, triazines, urea-derived herbicides and insecticides, a carbamoyl oxime, EI phtalimide, an acyl alanine, an organophosphorus insecticide and a uracil-derived compound, all of them potential pollutants of natural waters and soils. The analytes were separated on a C-18 60 Angstrom, 4 mu m (3,9 mm id x 300 mm) column with an acetonitrile-water based gradient elution program. To this end statistical model of linear regression was used. Limits of detection determined by three different methods were compared. A linear relationship for all compounds was obtained at the concentration levels under study (between 0.030 and 0.120 ng mu L-1 for carbaryl and between 1,5 and 6,0 ng mu L-1 for captan). Analytical sensitivity ranged between 0,011 and 2,611 ng and limits of detection were in the range 0.04-9.2 ng. Spectral parameters used for identity and purity tests allowed to establish the limits of identification, ranging from 0.15 and 7.5 ng. The developed method would allow a wider number of pesticides to be added for their determination in waters, due to its ability to separate the analytes and its capacity for peak identification and quantification at very low concentration levels.