基质效应对有机磷农药测定的影响及其解决方法

该文以液液萃取-气相色谱法探讨了基质对乐果、甲基对硫磷、马拉硫磷和对硫磷4种有机磷测定的影响以及解决方法.研究表明,气相色谱法测定有机磷农药的过程中基质效应显著存在,其基质增强比例为1.01 ～3.46.基质效应由基质种类及含量、有机磷农药种类及浓度等因素决定,同时与萃取溶剂、测定条件(如衬管、进样口温度等)有关.不同萃取溶剂对有机磷农药的萃取效率不同,但均存在基质增强效应;当进样口温度为260 ℃时,可最大程度降低基质在衬管中的残留,且不造成有机磷农药的分解;衬管则应首选带玻璃棉的.实际样品/标准样品的交替进样方式可以降低基质效应强度,但难以达到回收率要求,而校正因子校正法及分析保护剂法则是降低或消除基质效应的可行办法.

Solutions to Matrix-induced Response Enhancement Effects in Organophosphorus Pesticides Analysis by Gas Chromatography

Matrix-induced response enhancement effects of dimethoate,parathion-methyl,malathion and parathion were studied by liquid-liquid extraction coupled with gas chromatography/flame photometric detection(GC/FPD).The response enhancement ratios ranged from 1.01 to 3.46 relative to standards prepared in a matrix-free solvent.The response enhancement effects were different for various pesticides,matrix type and concentrations,as well as the solvent type and the GC system parameters including the type,design and operating conditions of the injector.Different types of extraction solvents yielded different extraction efficiencies for organophosphorus(OP) pesticides,but the matrix-induced response enhancement existed in all cases.At an injection temperature of 260 ℃,the pesticide residue in the liner was reduced to a great extent,without decomposing the OP pesticides.A liner with glass fiber should be the first choice.Matrix-induced enhancement effects can be reduced by injecting sample extracts and standards alternatively,but usually recovery was not better.The most effective solutions are the use of either matrix-matched standards or analyte protectants for calibration.