建立了水中4种环形和2种线形硅氧烷的顶空固相微萃取/气相色谱-质谱联用分析方法.考察了萃取纤维、萃取温度、萃取时间、水样pH值、解析时间、盐效应等因素对实验结果的影响.优化后的条件为:40mL水、40 μL内标(M4Q,500 μg/L)、NaCl(0.1 g/mL)加入60 mL顶空瓶中,选用65μm聚二甲基硅氧烷-二乙烯基苯(PDMS/DVB)纤维于24℃顶空萃取45 min.萃取完成后将纤维插入气相色谱进样口,于200℃解吸2 min进行定性、定量分析.结果表明,6种目标物的方法检出限为(LOD)2.6～7.8 ng/L,回收率为82％～ 96％,相对标准偏差(RSD)为1.1％～7.9％.%A headspace solid-phase microextraction (HS - SPME) coupled with gas chromatography -mass spectrometric ( GC - MS) method was developed for the analysis of four cyclic ( D3, D4, D5 and D6) and two linear volatile methyl siloxanes(L3 and L4) in aqueous samples. Parameters affecting the performance of HS - SPME/GC - MS, including fiber coating, desorption time, pH value, extraction temperature, extraction time and salinity, were studied. The optimum conditions were as the follows; 40 mL of water sample was placed in a 60 mL headspace vial containing a magnetic stir bar. 40 pX of 500 p-g/L internal standard (M4Q) and 0. 1 g/mL NaCl were added into vial, and then the vial was tightly sealed with a Teflon septum. HS - SPME with PDMS/DVB fiber was carried out at 24 t for 45 min. After the extraction, the fiber was removed from the vial, and inserted into the injection port of GC - MS system for thermal desorption (200 ℃, 2 min) and analysis. The method detected limits ( LOD) of six target compounds ranged from 2. 6 ng/L to 7. 8 ng/L. Their recoveries ranged from 82% to 96% with relative standard deviations ( RSDs, n = 5 ) of 1.1% -7. 9% . The results indicated that the method was simple, rapid, sensitive, and was suitable for the determination of volatile methyl siloxanes in aqueous samples. With the optimized method, the six target compounds were measured in 24 aqueous samples collected from Qinghe WWTP and Qinghe River. L4, D3, D4, D5 and D6 were detectable with concentrations of 0. 07 -0.21, 0.07 -0.59, 0.05-4.30, 0.02-7.60, 0.04-7.13 μg/L, respectively.
展开▼
