加速溶剂萃取-气相色谱-质谱法测定土壤中苯胺的部分前处理问题

为了探究土壤中苯胺回收率测定偏低的难点,笔者针对《土壤和沉积物 苯胺类和联苯胺类的测定 液相色谱-三重四极杆质谱法(征求意见稿)》中前处理阶段的问题,在优化部分前处理条件的基础上,研究土壤吸附、内标加入的时机以及还原剂(五水合硫代硫酸钠)和氨水对苯胺回收率的影响。结果表明:土壤吸附是导致苯胺加标回收率偏低的重要因素,与空白加标相比,含有一定量有机质的砂质壤土基体加标回收率减少了42.05%~60.89%。内标在不同阶段加入会对苯胺回收率产生显著影响,主要是由前处理过程中的基体吸附和挥发损失导致。加入还原剂和氨水对空白加标的苯胺回收率无显著影响,但对于含有一定量有机质的砂质壤土,加入氨水后苯胺加标回收率增加了59.57%,具有显著影响。

Some Pre-treatment Problems of Accelerated Solvent Extraction-Gas Chromatography-Mass Spectrometry for the Determination of Aniline in Soil

In order to explore the difficulty that the determination of aniline recovery rate in soil is low,the author addressed the problems in the pretreatment stage of Determination of Aniline and Benzidine in Soil and Sediments by Liquid Chromatography-Triple Quadrupole Mass Spectrometry (Draft for Comment), based on the optimization of some pretreatment conditions,the effects of soil adsorption, internal standard addition at different stages, and addition of reducing agent (sodium thiosulfate pentahydrate) and ammonia on the recovery rate of aniline were studied.It was found that: Soil adsorption is an important factor leading to the low recovery rate of aniline. Compared with blank addition, the recovery rate of sandy loam matrix with a certain amount of organic matter was reduced by 42.05%-60.89%. The addition of internal standards at different stages will have a significant impact on the recovery rate of aniline,which is mainly due to the matrix adsorption and volatilization loss during the pretreatment process. The addition of reducing agent and ammonia water had no significant effect on the recovery rate of blank spiked aniline, but for sandy loams with a certain amount of organic matter, the recovery rate of aniline spiked after adding ammonia water increased by 59.57%,which had a significant effect.