Analysis of benzimidazole anthelmintics in livestock foods by HPLC/MS/MS

A simple, selective and sensitive liquid chromato-graphic ion-trap mass spectrometry (LC-MS-MS) method was developed for the determination of benzimidazole anthelmintics, albendazole, 5-propyl-sulfonyl-1H-benzimidazole-2- amine, flubendazole, mebendazole, oxibendazole, thiabendazole, 5-hydroxy-thiabendazole, and triclabendazole, 5-chloro-6-(2,3-dichloro-phenoxy)- benzimidazole-2-one in livestock foods. LC separation was carried out on a Discovery HS F5 column (150 x 2.1 mm) by using 0.2% formic acid- acetonitrile (50:50) as the mobile phase at a flow rate of 0.2 ml/min. Detection was carried out on an ion-trap mass spectrometer by a multiple reaction monitoring (MRM) mode and an enhanced product ion (EPI) mode via electrospray ionization (ESI). The calibration graphs for benzimidazole anthelmintics were rectilinear from 0.01 to 10 ng with the MRM mode. The precursor ion and product ions obtained under the EPI mode were key criteria to confirm the identity of benzimidazole anthelmintics in samples. The EPI mode detection limits of benzimidazole anthelmintics were 0.005 to 0.05 ng.