Determination of neonicotinoid insecticides residues in bovine milk samples by solid-phase extraction clean-up and liquid chromatography with diode-array detection

In this paper we have developed an analytical method for the simultaneous determination of four nicotinoid insecticides [acetamiprid (ACT), imidacloprid (ICL), thiacloprid (TCL) and thiamethoxam (TMX)] in bovine whole milk. These analytes were extracted, in a single step with dichloromethane, from fortified milk samples, using Chem Hut cartridges, containing diatomaceous earth material. Insecticide's determination and quantification were performed by HPLC with diode-array detection (DAD). Average recoveries of the four insecticides from bovine milk samples were between 85.1 and 99.7% at spiking levels 0.01, 0.05 and 0.1 mg kg(-1). Relative standard deviations (RSDs) were no larger than 10% for all of the recovery tests. The calculated limits of quantitation (LOQ) ranged from 0.01 to 0.04 mg kg(-1) for the four insecticides, being equal to or lower than the maximum residue limits (MRIs) established by European legislation (0.01-0.05 mg kg(-1)). The developed method is linear at concentrations within the tested interval, with coefficients of determination higher than 0.9990. According to Commission Decision 2002/657/EC, decision limit (CC alpha) and detection capability (CC beta) have been calculated. The proposed method is rapid,simple and could be utilized for the routine analysis of pesticides residues. (c) 2008 Elsevier B.V. All rights reserved.