Food Research Laboratory , Centre for Food Safety, Food and Environmental Hygiene Department , 4/F Public Health Laboratory Centre, 382 Nam Cheong Street , Hong Kong.
J Agric Food Chem. 2018 Mar 21;66(11):3009-3018. doi: 10.1021/acs.jafc.7b06118. Epub 2018 Mar 5.
Suspected nontargeted pyrrolizidine alkaloids (PAs), without analytical reference standard, were observed and interfered with the determination of targeted PAs in complex food matrices, especially for spices samples. Selectivity and applicability of multiple reaction monitoring (MRM) transitions, multistage fragmentation (MS3), and MRM with differential ion mobility spectrometry (DMS) for eliminating false positive identifications were evaluated. Afterward, a selective and sensitive LC-MS/MS method for the determination of 15 PAs and 13 PA N-oxides in foodstuffs was developed. The sample preparation and cleanup are applicable to a wide range of foodstuffs, including cereal products, dairy products, meat, eggs, honey, tea infusion, and spices. Freezing-out of the raw extract and the water/acetonitrile washing steps in a solid phase extraction was found to efficiently remove complex matrices. The method was validated at 0.05 μg kg for general food and 0.5 μg kg for spices, with reference to the Eurachem Guide. The estimated limit of quantifications of different PAs was in the range of 0.010-0.087 μg kg for general food and 0.04-0.76 μg kg for spices. Isotopically labeled PAs were used as internal standards to correct the variation of PAs/PANs performance in different food commodities. Matrix effects observed in complex food matrices could be reduced by solvent dilution. Recoveries of PAs and PA N-oxides were all seen within 50-120%.
疑似非靶向吡咯里西啶生物碱（PAs），没有分析参考标准，在复杂食品基质中观察到并干扰了靶向 PAs 的测定，尤其是对于香料样品。评估了多反应监测（MRM）转换、多级碎裂（MS3）和带有差分离子迁移谱（DMS）的 MRM 对消除假阳性鉴定的选择性和适用性。随后，开发了一种用于测定食品中 15 种 PAs 和 13 种 PA N-氧化物的选择性和灵敏的 LC-MS/MS 方法。样品制备和净化适用于广泛的食品，包括谷物产品、乳制品、肉类、蛋类、蜂蜜、茶浸液和香料。在固相萃取中，冷冻原始提取物和水/乙腈洗涤步骤被发现可有效地去除复杂基质。该方法按照 Eurachem 指南在 0.05μgkg 对一般食品和 0.5μgkg 对香料进行了验证。不同 PAs 的估计定量限范围为 0.010-0.087μgkg 一般食品和 0.04-0.76μgkg 香料。同位素标记的 PAs 被用作内标，以校正不同食品商品中 PAs/PANs 性能的变化。通过溶剂稀释可以降低复杂食品基质中的基质效应。PAs 和 PA N-氧化物的回收率均在 50-120%之间。
