分散固相萃取-在线凝胶色谱-气相色谱-质谱联用法快速检测紫菜中的农药多残留

建立了紫菜中农药多残留的在线凝胶色谱-气相色谱-质谱联用（GPC-GC/MS）检测方法。以有机氯、有机磷、三嗪类和菊酯类的19种农药为目标物，对比了丙酮、丙酮/二氯甲烷（1:1，v/v）和乙腈3种有机溶剂的提取效果，通过石墨化炭黑粉（GCB）和N-丙基乙二胺粉（PSA）分散固相萃取净化和GPC在线净化，气相色谱-质谱联用法分析，外标法定量。结果表明，此方法实现了在线净化与分析检测的自动化，缩短了分析时间。分析物在10~1000 μg/L范围内线性关系良好，相关系数r>0.995；采取GPC大体积进样和气相色谱进样口的程序升温方式提高了检测灵敏度，检出限为0.005~0.03 mg/kg。方法的平均添加回收率在70%~120%之间，相对标准偏差（RSD）均小于15%。该方法简单、快速、具有良好的回收率和重复性，适用于紫菜样品中农药多残留的快速灵敏检测。

Rapid determination of pesticide multiresidues in porphyra by dispersive solid-phase extraction coupled with online gel permeation chromatography-gas chromatography-mass spectrometry

A rapid method for the simultaneous identification and quantification of pesticide multiresidues in porphyra was developed using gel permeation chromatography (GPC) coupled to gas chromatography-mass spectrometry (GPC-GC/MS). Nineteen pesticides (organochlorines, organophosphoruses, triazines and pyrethroids) were selected as the target analytes. The pretreatment method was applied consisting of organic solvent extraction followed by dispersive solid-phase extraction with graphitized carbon black (GCB) and primary secondary amine (PSA) adsorbents. GPC was also employed online to remove the large molecules such as pigments and lipids. The quantitative analysis was carried out by external standard method using gas chromatography coupled with mass spectrometry in selective ion monitoring (SIM) mode. Moreover, a large volume of sample was allowed to be injected using the program of GPC programmed-temperature vaporizer of gas chromatography to improve the sensitivity of measurements. The results showed that the calibration curves were linear (r >0.995) in the range of 10-1000 μg/L for all the pesticides. The limits of detection (LODs) for the pesticides in porphyra were from 0.005 to 0.03 mg/kg, and the average recoveries were between 70% and 120%. The advantages of the method are simple, sensitive and shorter operation time for analysis of pesticide residues in porphyra samples.