对水中有机磷农药样品保存方法的优化

优化了对水中11种有机磷农药检测的样品保存方法。加标水样在4℃下保存一定时间后，通过液液萃取，气相色谱-质谱（选择离子模式）法测定有机磷农药的回收率。在不加入稳定剂的情况下，水样的保存时间不宜超过16h。为延长样品的保存时间，向水样中加入有机溶剂和pH调节剂作为稳定剂。实验结果表明，当在1000ml样品中加入10ml正己烷和10mlpH=3．6的醋酸-醋酸钠缓冲溶液时，可以将样品保存时间延长至48h。为验证方法的有效性，以地表水作为实际水样，加标浓度水平在0．2μg／L和0．04μg／L时，48h后的平均加标回收率在76．2％-95．0％之间，RSD在2．4％-7．2％之间。

Optimization of Sample Preservation Method for Organophosphorus Pesticides in Water

This study optimized the preservation methods for 11 organophophorus pesticide samples in water. Water samples were stored at 4℃, and the spiked recoveries were determined by liquid - liquid extraction and GC/MS analysis. Water samples can be preserved for no more than 16 h without stabilizing agent. Solvents and pH regulating agents were added into water samples as stabilizing agents in a bid to extend the preservation time. The results showed that when 10 ml n - hexane and 10 ml acetic acid - sodium acetate buffer solution were added into 1 000 ml water sample as stabilizing agent, the preservation time can be extend- ed to 48 h. The effectiveness of this method was validated by surface water samples that were spiked at 0. 2μg/L and 0. 04μg/L, and the average spiked recoveries after 48 h were between 76. 2% and 95.0% with RSDs between 2. 4% and 7.2%.