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建立了超声萃取-气相色谱/质谱法同时测定土壤中3种典型季胺盐化合物十二烷基三甲基氯化胺(DTAC)、十六烷基三甲基溴化胺(CTAB)、双十二烷基二甲基氯化胺(DDAC)的分析方法。采用电子轰击(EI)-选择离子检测(SIM)进行定量分析,特征离子为m/z 58,212。考察了萃取剂种类、辅助萃取剂直链烷基苯磺酸(LAS)浓度、萃取剂pH值(0.5~7.0)、萃取次数(1,2,3)以及净化柱成分对萃取效率的影响。最佳萃取条件为,以甲醇为萃取剂,以HCl调至pH 3.5,LAS浓度为40μg/L,超声萃取2次,每次10 mL甲醇,20 min,萃取液采用中性氧化铝柱净化。3种目标化合物的线性范围在0.02~2.0 mg/L之间;方法检出限为1.2~4.5μg/kg。以此方法测定南方某矿区尾矿渣及周边水稻土、赤红壤等样品,目标化合物的含量在0.24~0.41 mg/kg之间,不同加标水平(0.2,0.5和1.0 mg/kg)回收率在76%~113%之间,相对标准偏差在1.1%~12.9%之间。
A method for the simultaneous determination of three typical quaternary ammonium compounds, DTAC, CTAB and CTAB in soil by ultrasonic extraction-gas chromatography-mass spectrometry was established. Analysis of dodecyldimethyl ammonium chloride (DDAC). Quantitative analysis was performed using Electron Impact (EI) - Selected Ion Separation (SIM) with characteristic ions of m / z 58,212. The effects of extractant type, LAS concentration, pH value of extractant (0.5 ~ 7.0), extraction times (1, 2 and 3), and column components on extraction efficiency were investigated. The optimum extraction conditions were as follows: methanol as extractant, pH 3.5 with HCl, LAS concentration 40μg / L, ultrasonic extraction twice with 10 mL of methanol for 20 min. The extract was purified by neutral alumina column. The linear range of the three target compounds ranged from 0.02 mg / L to 2.0 mg / L. The detection limits were 1.2-4.5 μg / kg. This method was used to determine the tailing slag, the surrounding paddy soil and the laterite soil in a mining area in the south of China. The target compound content was between 0.24 and 0.41 mg / kg. The recoveries at different spiked levels (0.2, 0.5 and 1.0 mg / kg) 76% ~ 113%, the relative standard deviation of 1.1% ~ 12.9%.