Yudina T V, Fedorova N E, Larkina M V, Egorchenkova O E, Rogacheva C K
Gig Sanit. 2016;95(11):1108-12.
In the work there are presented results of studies on the validation of the gas chromatographic (GC) methodfor the determination of chlorothalonil residue amounts in peaches with the use of electron capture detector (ECD). For the analytical control there was selected such stone fruit crop as the peach, referring to the crops, the most contaminated with residue amounts ofpesticides. There was justified the necessity of the inclusion in the procedure of the detection of the method of confirmation, based on mass spectrometry detection (MSD) (the type of ionization - electron impact). The significant source of the obtaining of incorrect data in the identification with the use of ECD of ions are shown to be phthalates, visualized in the chromatogram as intense and/or broad peaks. Mass spectra of compounds of the class ofphthalates are characterized by the dominant peak of the ion with the value of (mass/ charge) 149, just on this peak the detection of low molecular weight phthalates occurs in various matrices, on the spectrum there are also recorded typical ions corresponding to fragments of radical residues. The combination of the use of various types of the detection allows to prove that the revealed response (detector signal) is caused just by the analyte, but not the impurities, and optionally to optimize chromatographic conditions towards to the obtaining reliable results. The lower limit of the quantitation of chlorothalonil in peach fruits accounts for 0.01 mg/kg, determined with a signal/noise ratio of 10. The range of measured concentrations is volatile between 0.01-0.1 mg/kg, recovery rate of chlorothalonil from samples of peaches, established according to results of the analysis of model samples with the introduction of the substance in four points along the detection range, was 84-102%, the SD value of the repeatability varies in the range of 2.0-5.8%.
该研究工作展示了采用电子捕获检测器（ECD）测定桃子中百菌清残留量的气相色谱（GC）方法的验证结果。作为分析对照，选择了桃子这种核果类作物，因为此类作物农药残留量污染最为严重。基于质谱检测（MSD）（电离类型——电子轰击），论证了在检测程序中纳入确证方法的必要性。研究表明，在使用ECD进行离子鉴定时，邻苯二甲酸酯是获取错误数据的重要来源，其在色谱图中表现为尖锐和/或宽峰。邻苯二甲酸酯类化合物的质谱特征是离子（质荷比）149的主峰占主导，正是基于此峰，在各种基质中检测到低分子量邻苯二甲酸酯，质谱图上还记录了与自由基残基片段相对应的典型离子。多种检测方式的结合能够证明所显示的响应（检测器信号）确实是由分析物而非杂质引起的，并且可以根据需要优化色谱条件以获得可靠结果。桃子果实中百菌清的定量下限为0.01 mg/kg，在信噪比为10时测定得出。测量浓度范围在0.01 - 0.1 mg/kg之间波动，根据在检测范围内四个点引入该物质的模型样品分析结果确定，百菌清从桃子样品中的回收率为84 - 102%，重复性的SD值在2.0 - 5.8%范围内变化。
