Development of dispersive liquid-liquid microextraction method for the analysis of organophosphorus pesticides in tea

In this article, a new method for the determination of organophosphorus pesticides (OPPs) in tea was developed by using dispersive liquid-liquid microextraction (DLLME) and gas chromatography-flame photometric detection (GC-FPD). A mixture of acetonitrile and n-hexane was used as an extraction solvent for the extraction of OPPs from tea samples. When the extraction process was finished. the mixture of solvents was rapidly dispersed in water; target analyte was extracted to a small volume of n-hexane, using DLLME. Recovery tests were performed for concentration 5.0 mu g/kg. The recovery for each target analyte was in the range between 83.3 and 117.4%. The repeatability of the proposed method. expressed as relative standard deviation, varied between 3 and 7.8% (n = 3). The detection limit of the method for tea was found ranging from 0.030 to 1 mu g/kg for all the target pesticides. Compared with the conventional sample preparation method, the proposed method has the advantage of being quick and easy to operate, and has high-enrichment factors and low consumption of organic solvent. (C) 2009 Elsevier B.V. All rights reserved.