LC/ESI-MS/MS method for the identification and quantification of spinosad residues in olive oils

This paper reports the use of liquid chromatography/electrospray ionisation tandem mass spectrometry (LC/ESI-MS/MS) method for the identification and quantification of residues of the natural insect control agent Spinosad in olive oils. The method determines the active ingredients Spinosyns A and D and two minor metabolites Spinosyns B and K without laborious sample treatment. All four analytes are determined simultaneously in a single injection using positive electrospray ionisation LC-MS with multiple reaction monitoring (MRM). For the quantitative analysis of samples an external calibration curve was built. The calibration curves for each analyte were linear in the concentration range 20-500 ng/mL with a correlation coefficient ranging between 0.995 and 0.999. Results from spike and recovery experiments at levels of 100 and 200 ng/mL gave mean recoveries ranging from 87-116% with satisfactory precision (relative standard deviation (RSD) from 1-8%). The excellent selectivity and sensitivity allows quantification and identification of low levels of Spinosad in olive oils (limits of quantification (LOQs) 0.004-0.073). (C) 2010 Elsevier Ltd. All rights reserved.