In this study, four tree-nut allergens were identified using liquid chromatography-mass spectrometry (LC-MS/MS) with a reverse-phase XSelect HSS C18 SB column (100 mm x 2.1 mm, 3.5 µm) and corresponding guard column. The gradient solvent program employed 0.1% formic acid in water and 0.1% formic acid in acetonitrile, with a flow rate of 0.5 mL/min, a positive ion electrospray ionization (ESI+) source, and a multiple reaction monitoring (MRM) mode. The method was validated following the guidelines of AOAC International. Results showed that the method had good specificity, with calibration curves constructed in the concentration ranges of 30.5 - 1220 µg/g for almonds, 102 - 4080 µg/g for cashews, 128 - 5120 µg/g for hazelnuts, and 122 - 4880 µg/g for pistachios. Limits of detection were 9 µg/g for almonds, 30.6 µg/g for cashews, 38.4 µg/g for hazelnuts, and 36.6 µg/g for pistachios, while limits of quantification were 30.5 µg/g for almonds, 102 µg/g for cashews, 128 µg/g for hazelnuts, and 122 µg/g for pistachios. The repeatability and accuracy of the method met AOAC requirements. The method was used to analyze the content of four groups of nut allergens (almond, cashew, hazelnut, and pistachio) in ten cookie samples from the Hanoi area. Results indicated that three samples contained undeclared allergens on the food labels.
tree-nut allergen, LC-MS/MS, cookies.
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