Simultaneous determination of spirotetramat and its four metabolites in fruits and vegetables using a modified quick, easy, cheap, effective, rugged, and safe method and liquid chromatography/tandem mass spectrometry

A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for the simultaneous determination of spirotetramat and its four metabolites in fruits (apple, peach) and vegetables (cabbage, tomato, potato, cucumber), based on the use of liquid extraction/partition and dispersive solid phase extraction (dispersive-SPE) followed by ultrahigh-performance chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS), was established. Acidified acetonitrile (containing 1% (v/v) acetic acid) as the extraction solvent and simultaneous liquid-liquid partitioning formed by adding anhydrous magnesium sulfate (MgSO4) and anhydrous sodium acetate (NaOAc). The extract was then cleaned up by dispersive-SPE using graphitized carbon black (GCB) as selective sorbent. Further optimization of sample preparation and determination achieved recoveries of between 82 and 110% for all analytes with RSD values lower than 14% in apple, peach, cabbage, tomato, potato and cucumber at three levels (10, 100 and 1000 mu g/kg). The method showed excellent linearity (R-2 >= 0.9895) for all studied analytes. The determination of the target compounds was achieved in less than 6.0 min using an electrospray ionization source in positive mode (ESI+). The method is demonstrated to be convenient and reliable for the routine monitoring of spirotetramat and its metabolites in fruits and vegetables. (C) 2013 Elsevier B.V. All rights reserved.