建立了检测水中有机磷农药的离子迁移率谱仪预富集进样方法。预富集器由表面覆盖有吸附薄膜的微热板、聚四氟乙烯电路板和管座组成,具有操作简单,无需有机溶剂,自加热,热容小,功耗低等优点。以马拉硫磷检测为例,分析了富集器解吸升温速率和离子迁移率谱仪半透膜温度对检测结果的影响。采用高温短时脉冲加热和低温维持加热相结合的解吸方式,既可形成较高的进样浓度脉冲,又可减少进入漂移管的杂质,有利于提高离子迁移率谱仪检测灵敏度。实验表明:采用所述预富集及两阶段加热解吸进样方法,对水中马拉硫磷的检出限为3.9μg/L,达到了国家标准对水中有机磷检测的要求。
A method of sample preconcentration and introduction for an ion mobility spectrometer ( IMS) was proposed for the detection of organophosphorus pesticides ( OPPs) in water. The preconcentrator was composed of a microhotplate coated with an absorption film,a polytetrafluoroethylene ( PTFE) printed circuit board ( PCB) and a PTFE cylinder. It has the advantages of easy-operation,solvent-less,self-heating,low thermal capacity and low energy cost. The effects of the heating rate for absorption film and the semi-permeable membrane temperature on the response of IMS were analyzed for an example of the detection of malathion,a twostage desorption mode was adopted,in which the absorption film was first heated pulsely to a high temperature and then held at a low temperature. With the desorption mode,the sensitivity of IMS was improved due to the high sample concentration pulse and the low semi-permeable membrane temperature which leads to less impurity into the drift tube. Using the method,the detection limit for the malathion in water is 3. 9 μg/L, which meets the requirements of the national standards.