Determination of carbendazim and thiabendazole in environmental water samples using solid-phase extraction and LC/electrospray MS/MS

Carbendazim (MBC) and thiabendazole (TBZ) in environmental water samples we re simultaneously determined by a liquid chromatograph/tandem mass spectrom eter equipped with an electrospray ionization interface (LC/ESI-MS/MS). A s imple and rapid sample pretreatment procedure using solid-phase extraction was developed to minimize the ion-suppression effect and to enrich analyte compounds. Both MBC and TBZ were quantitatively retained on a solid-phase e xtraction cartridge (Oasis HLB). The cartridge was washed with 3 ml of a 30 vol% methanol solution and then with 3 ml of water, and subsequently dried under a vacuum. MBC and TBZ retained on the cartridge were recovered by el ution with 4 ml of ethyl acetate. The eluate was taken to dryness under a n itrogen stream before being re-dissolved in 1 ml of a water/methanol (1 : 1 ) solution. The solution was analyzed by LC/ESI-MS/MS. The results of analy ses of spiked MBC and TBZ in aqueous solution demonstrate the applicability of the proposed method to environmental aqueous solutions, such as river w ater and the discharge of sewage treatment plant (DSTP). Detection limits o f 0.32 ng/1 for MBC and 0.93 ng/1 for TBZ in river water, and 5.6 ng/1 for MBC and 4.9 ng/1 for TBZ in DSTP have been achieved. The results of overall recovery tests showed that the recovery of deuterated MBC-d(3), the spiked internal standard, was 85.4%, and that the relative standard deviation (RS D) was 11%. The recoveries of MBC for river water spiked at 5 ng/1 and 50 n g/1 were 102% and 104%, and for DSTP spiked at 250 ng/1 was 106%, respectiv ely, and their RSD ranged from 1.9% to 3.4%. The recoveries and RSD of TBZ ranged from 78.9% to 136%, and from 1.8% to 4.8%, respectively.