Development of microextraction techniques in combination with GC-MS/MS for the determination of mycotoxins and metabolites in human urine

Simple and highly efficient sample preparation procedures, namely, dispersive liquid-liquid microextraction and salting-out liquid-liquid extraction for the analysis of ten Fusarium mycotoxins and metabolites in human urine were compared. Various parameters affecting extraction efficiency were carefully evaluated. Under optimal extraction conditions, salting-out liquid-liquid extraction showed a better accuracy (84-96%) and precision (<14%) than dispersive liquid-liquid microextraction. Hence, a multibiomarker method based on salting-out liquid-liquid extraction followed by gas chromatography with tandem mass spectrometry was proposed. Satisfactory results in terms of validation were achieved. The method resulted in low limits of detection and quantitation within the range of 0.12-4 and 0.25-8 mu g/L, respectively. The method accuracy and precision were evaluated at three spiking levels (8, 25 and 100 mu g/L) and the recoveries were in a range from 70 to 120% with relative standard deviations lower than 15%. Matrix effect was evaluated and matrix-matched calibrations were used for quantitation purpose. The developed method was applied in 12 human urine samples as a pilot study before and after sample treatment with beta-glucuronidase before the analysis to quantify the mycotoxin conjugates. Total deoxynivalenol (free + conjugated) was found in 83% of samples at an average concentration in positive samples of 31.6 mu g/L.