Dopant-Assisted Atmospheric Pressure Photoionization of Patulin in Apple Juice and Apple-Based Food with Liquid Chromatography-Tandem Mass Spectrometry

A dopant-assisted atmospheric pressure photoionization (APPI) with liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed to determine patulin in apple juice and apple-based food. Different dopants, dopant flow rates, and LC separation conditions were evaluated. Using toluene as the dopant, the LC-APPI-MS/MS method achieved a linear calibration from 12.5 to 2000 mu g/L (r(2) > 0.99). Matrix-dependent limits of quantitation (LOQs) were from 8 mu g/L (solvent) to 12 mu g/L (apple juice). [C-13]-Patulin-fortified apple juice samples were directly analyzed by the LC-APPI-MS/MS method. Other apple-based food was fortified with [C-13]-patulin, diluted using water (1% formic acid), centrifuged, and filtered, followed by LC-APPI-MS/MS analysis. In clear apple juice, unfiltered apple cider, applesauce, and apple-based baby food, average recoveries were 101 +/- 6% (50 mu g/kg), 103 +/- 5% (250 mu g/kg), and 102 +/- 5% (1000 mu g/kg) (av +/- SD, n = 16). Using the suggested method, patulin was detected in 3 of 30 collected market samples with concentrations ranging from