Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada.
J Agric Food Chem. 2015 May 13;63(18):4464-77. doi: 10.1021/jf506212j. Epub 2015 Apr 21.
A fast and sensitive direct immersion-solid-phase microextraction-gas chromatography-time-of-flight mass spectrometry (DI-SPME-GC-ToFMS) method for the determination of multiresidue pesticides in grapes employing a PDMS-modified PDMS/DVB coating was developed utilizing multivariate approaches for optimization of the most important factors affecting SPME performance. A comprehensive investigation of appropriate internal standards using a bottom-up approach led to the selection of suitable compounds that adequately covered a range of 40 pesticides pertaining to various classes. The validated method yielded good accuracy, precision, and sensitivity and has been successfully applied to the analysis of commercial samples. With regard to the limitations of the proposed method, the DI-SPME method did not provide a satisfactory performance toward more polar pesticides (e.g., acephate, omethoate, dimethoate) and highly hydrophobic pesticides, such as pyrethroids. Despite the challenges and limitations encountered by this method, the practical aspects of the PDMS-modified coating demonstrated here create new opportunities for SPME applied in food analysis.
采用 PDMS 改性的 PDMS/DVB 涂层，建立了一种快速灵敏的直接浸入式固相微萃取-气相色谱-飞行时间质谱（DI-SPME-GC-ToFMS）方法，用于测定葡萄中的多残留农药。采用多元方法优化了影响 SPME 性能的最重要因素，对合适的内标物进行了全面的研究。采用自下而上的方法选择了合适的化合物，这些化合物充分涵盖了 40 种不同类别农药的范围。经验证的方法具有良好的准确性、精密度和灵敏度，并已成功应用于商业样品的分析。关于该方法的局限性，DI-SPME 方法对极性更强的农药（如乙酰甲胺磷、氧乐果、乐果）和高疏水性农药（如拟除虫菊酯）的性能并不令人满意。尽管该方法存在挑战和局限性，但这里展示的 PDMS 改性涂层的实际方面为 SPME 在食品分析中的应用创造了新的机会。
