Determination of the limits of identification and quantitation of selected organochlorine and organophosphorous pesticide residues in surface water by full-scan gas chromatography/mass spectrometry

In this work, we report a reliable method for quantitation and determination of the limits of identification of 14 organochlorine and organophosphorous pesticide (OPP) residues in surface water. The method features the simultaneous identification and quantitation of targeted pesticides and the possibility of identification of any other eluting compounds. The method is based on liquid-liquid extraction (LLE) with a mixture of petroleum ether and dichloromethane (70:30, v/v) followed by gas chromatographic separation and a full-scan mass spectrometric detection (GC-MS). The method presents a new validation parameter, limit of identification (LOI) which is defined for our purpose as the lowest analyte concentration that yields a library searchable mass spectrum. The method is linear over the range 0.048-1.20 μg L−1 for nine pesticides and 0.024-0.60 μg L−1 for the other five pesticides. Correlation coefficients vary between 0.988 and 0.998. Limits of detection (LODs) vary between 0.005 and 0.05 μg L−1 for 4,4′-DDT and LOIs vary between 0.012 and 0.048 μg L−1.