Simultaneous determination of 117 pesticides and 30 mycotoxins in raw coffee, without clean up, by LC ESI MS/MS analysis.
This paper describes the optimization and validation of an acetonitrile based method for simultaneous extraction of multiple pesticides and mycotoxins from raw coffee beans followed by LC ESI MS/MS determination. Before extraction, the raw coffee samples were milled and then slurried with water. The slurried samples were spiked with two separate standard solutions, one containing 131 pesticides and a second with 35 mycotoxins, which were divided into 3 groups of different relative concentration levels. Optimization of the QuEChERS approach included performance tests with acetonitrile acidified with acetic acid or formic acid, with or without buffer and with or without clean up of the extracts before LC ESI MS/MS analysis. For the clean up step, seven d SPE sorbents and their various mixtures were evaluated. After method optimization a complete validation study was carried out to ensure adequate performance of the extraction and chromatographic methods. The samples were spiked at 3 concentrations levels with both mycotoxins and pesticides (with 6 replicates at each level, n 6) and then submitted to the extraction procedure. Before LC ESI MS/MS analysis, the acetonitrile extracts were diluted 2 fold with methanol, in order to improve the chromatographic performance of the early eluting polar analytes. Calibration standard solutions were prepared in organic solvent and in blank coffee extract at 7 concentration levels and analyzed 6 times each. The method was assessed for accuracy (recovery precision (RSD% selectivity, linearity (r2) limit of quantification (LOQ) and matrix effects
Analytica chimica acta