液液萃取-气相色谱/质谱法同时测定水中3种季胺盐化合物

Simultaneous Extraction and Determination of Three Quatermary Ammonium Compouds in Water Using Liquid-liquid Exaction and Gas Chromatography-Mass Spectrometry

建立了液液萃取-气相色谱/质谱同时测定水中3种典型季胺盐化合物十二烷基三甲基氯化铵（DTAC）、十六烷基三甲基溴化铵（CTAB）、双十二烷基二甲基氯化铵（DDAC）的分析方法。采用电子轰击（EI）-选择离子模式（SIM）进行定性与定量分析,DTAC和CTAB的特征离子为m/z 58,DDAC的特征离子为m/z 212。考察了萃取剂种类、萃取次数、pH值以及盐度对萃取效率的影响。以HCl及30%NaCl溶液调节水样pH值为1.5及盐度为3%,以5 mL三氯甲烷萃取2次,3种目标化合物的线性范围在0.01~2.0 mg/L之间,检出限LOD（S/N=3）为2.5~8.5μg/L。以此方法测定自来水、湖水、河水、选矿废水样品,3种目标化合物的含量在0.06~2.45 mg/L之间,不同加标水平（0.2,0.5和1.0 mg/L）回收率在65%~113%之间,相对标准偏差在3.8%~23.0%之间。

An analytical method was developed for the simultaneous extraction and determination of three quatermary ammonium compouds （ QACs ） in water samples using liquid-liquid extraction and gaschromatography mass spectrometry. The qualitative and quantitative analysis of the three analytes （ dodecyltrimethylammonium chloride （ DTAC） , CTAB and didodecyl-dimethyl-ammonium chloride （ DDAC） was conducted by application of EI Mass spectra and selected ion monioring （ SIM） . Characteristic ion of the first two （DTAC, CTAB） and the latter was m/z 58, and the characteristic ion of DDAC was m/z 212. To achieve optimum extraction efficiency, several impact factors including different types of extractants, extraction times, pH value and salinity in water sample matrixs were investigated. In the optimized extraction conditions, pH and salinity of water sample was adjusted to 1 . 5 and 3% respectively using hydrochloric acid and sodium chloride , then the processed water sample was extracted by chloroform twice with 5 mL every time in a 125 mL separatory funnel. Good linear relationships of all the three analytes were obtained in the range of 0. 01-2. 0 mg/L. The limits of determination （ LOD, S/N=3 ） was 2. 5-8. 5 μg/L. The method was used to analyse real water samples collected from running water, lake water, river water and beneficiation water. Results of determination displayed the concerntrations of the three analytes in real water samples ranged from 0. 06 mg/L to 2. 45 mg/L, and their recoveries ranged from 65% to 113% with relative standard deviations （RSD） 3. 8%-23% in three different spiked concentrations （0. 2, 0. 5 and 1. 0 mg/L）.