The HPLC-DAD and GC/MS methods were successfully used for the identification and characterization of the impurities in an agrochemical insecticide, bifenthrin technical. Three impurities ranging from 0.175%-0.541% were detected by the HPLC-DAD method. The LC/MS technique with ESI or APCI source failed to detect the impurities detected by HPLC-DAD, due to lack of ionization in ESI or APCI. The three impurities were enriched by prep-HPLC, and then their structures were elucidated based on the GC/EIMS and CIMS data. The EI mass spectra of bifenthrin and its impurities displayed molecular ion and provided structure indicative fragment ions; the CIMS data further confirmed their molecular weight. The identity of the impurity 1 was further confirmed by the synthesis of the authentic sample followed by NMR and GC/MS data.
Keywords: EI/CI ionization; GC/MS; bifenthrin technical; impurities; prep-HPLC.
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