Synthesis and use of deuterated fenamiphos and its metabolites as internal standards for mass spectrometric analysis in water

The applications of mass spectrometry (MS) are increasing in environmental analysis, pesticides measurement in particular. To take full advantage of the capabilities of MS it is important to have available labeled standards that enhance the performance of the quantitative analysis, increasing its accuracy and precision. We synthesized a series of deuterated internal standards corresponding to fenamiphos (Ia) and some of its metabolites, using rapid procedures and inexpensive materials. The use of 3-fluoro-3-(heptafluoropropyl)-2-(nonafluorobutyl)-cis-oxaziridine (IV) was particularly attractive for the preparation of oxidative metabolites of fenamiphos (Ia), analytical and deuterated standards. We used these compounds for the analysis of these pollutants in water. We used solid-phase extraction, testing several materials, and supercritical fluid extraction techniques. The analysis was done by gas chromatography-mass spectrometry, with the selected ion monitoring (SIM) technique, obtaining good results with the oxidative metabolites of compound Ia (compounds IIa and IIIa). For the more polar metabolites Ib, IIb and IIIb, liquid chromatography-mass spectrometry analysis in the SIM mode gave the best result.