Deuterated internal standards for gas chromatographic-mass spectrometric analysis of polar organophosphorus pesticides in water samples

Abstract It is essential to know whether drinking water contains any pesticides up to concentrations close to the European Union limit of 0.1 μg/l, in order to protect the population. Mass spectrometry (MS) using a suitable internal standard (I.S.) should improve the quantitative analysis of pesticides, the I.S. circumventing loss of compounds during the analytical procedure and correcting the analytical variability. In this study we verified this assumption in GC-MS, synthesising specific internal standards for four organophosphorus pesticides with poor stability, comparing the performances with and without the I.S.