Determination of Clothianidin Residues in Inflorescences of Common Horse Chestnut (Aesculus hippocastanum L.) by Ultra-Performance Liquid Chromatography with Tandem Mass Detection (UPLC-MS/MS)

Clothianidin ((E)-1 -(2 -chloro-1,3 -thiazol-5 -ylmethyl)-3 -methyl-2 -nitroguanidine) belongs to the group of nitroguanidine insecticides. It has been found a very effective agent against various noxious insects, however may be also highly toxic to the useful ones. Horse chestnut leaf miner (Cameraria ohridella, [1]) is a new pest of the common horse chestnut (Aesculus hippocastanum L.). In Poland in 2004, the study on the applicability ofclothianidin into-soil injections under a canopy of common horse chestnut trees in the pest control was undertaken. In this paper, a simple, rapid, very sensitive and highly repeatable method for determination of clothianidin residues in the inflorescence of common horse chestnut using RP-UPLC-MS/MS technique has been described. The procedure consisted of solid phase extraction (SPE) ofclothianidin from either fresh or dry plant material using a SPE Chem--Elut 1020 column, chromatographic separation of the obtained eluate on anAcquity BEH C 18 column, followed by a tandem mass detection. Recoveries ofclothianidin in the samples spiked at the level of 0.01 mg kg -1 averaged at 83.7 and 89.8% for fresh and dry mass, respectively, while in the samples spiked at the level of 0.1 mg kg -1 they equaled 94.4 for fresh and 93.6% for a dry material. Relative standard deviations ranged from 2.1 to 5.7% for fresh samples and from 3.6 to 4.1% for dry plant material. The limit of quantification for clothianidine was 0.005 mg kg -1 .