冷冻干燥法在气相色谱法测定干枣中7种拟除虫菊酯类农药残留中的应用

The application of freezing-drying method for determination of 7 kinds of pyrethroid pesticides residues in dried jujube by gas chromatography

目的建立冷冻干燥-气相色谱法测定干枣中7种拟除虫菊酯类农药。方法试样经冷冻干燥后粉碎,乙腈超声提取,离心,弗罗里硅土柱净化后气相色谱仪直接测定,外标法定量,阳性样品经气相色谱质谱联用法确证。结果加标回收率范围为72.3%~120.1%,相对标准偏差(RSDs)在2.1%~8.1%。将本方法用于实际样品分析,61份干枣中联苯菊酯检出5份,甲氰菊酯检出7份,高效氯氟氰菊酯检出22份,氯氰菊酯检出5份,氰戊菊酯检出6份,氟氯氰菊酯和溴氰菊酯均未检出。结论此方法准确度高,可用于干枣中7种拟除虫菊酯类农药残留的测定。

Objective To establish a method for the determination of 7 kinds of pyrethroid pesticides in dried jujube by freezing-drying method and gas chromatography. Methods After drying up by freezing-drying method, samples sequentially covered extraction by acetonitrile, centrifugation, Florisil columns cleanup, and determined by gas chromatography. Using the external standard method for quantitative analysis, the positive samples were confirmed by gas chromatography-mass spectrometry. Results The present method showed acceptable recoveries of 72.3%~120.1%, with relative standard deviation(RSDs) ranging from 2.1% to 8.1%. The method was applied to real sample analysis. In all 61 samples, bifenthrin was found in 5 samples, fenpropathrin was found in 7 samples, λ-cyhalothrin was found in 22 samples, cymperator was found in 5 samples and fenvalerate was found in 6 samples. In addition, cyfluthrin and deltamethrin were not detected in the present study. Conclusion This method is demonstrated to be accurate, which can be applied in the determination of 7 kinds of pyrethroid pesticides in dried jujube.