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1、MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,空气中苯、甲苯和二甲苯的测定,溶剂解吸-气相色谱法实习 指导老师：郑 丹,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,【目的和要求】掌握气相色谱法测定空气中苯、甲苯和二甲苯的基本原理和操作技术；熟悉气相色谱仪器的基本操作和参数设置；
2、了解玻璃毛细管色谱住条件的优化；出峰时间定性的方法。,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,【原理】空气中的苯、甲苯、二甲苯用活性碳管采集，二硫化碳解吸后进样，经色谱柱分离，氢焰离子化检测器检测，以保留时间定性，峰面积定量。,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,
3、【仪器及试剂】1.活性碳采样管：675mm，溶剂解吸型，内装100mg/50mg 活性碳。2.空气采样器：QC-2B型大气采样仪，流量。3.玻璃器皿：具塞比色管，10ml；移液管，10mL，微量注射器：10、5l。4.二硫化碳：色谱鉴定无干扰杂峰。5.苯、甲苯和二甲苯：分析纯，纯度99.5%以上。,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,MOE Key Laboratory of Environmental&Health,Inst
4、itute of Environmental Medicine,School of Public Health,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,6.气相色谱仪（GC Agilent 6890N）条件：进样口250，分流比（30.0：1），载气：高纯氮气，玻璃毛细管柱：HP-5毛细管色谱柱，恒流模式，流量：1.2ml/min。柱温 80，保持7min。氢焰离子化检测器（FID）：300。,MOE Key Laboratory
5、 of Environmental&Health,Institute of Environmental Medicine,School of Public Health,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,【分析步骤】1.样
6、品处理：将采过样的前后段活性碳分别放入溶剂解吸瓶中，各加入1.0ml二硫化碳，塞紧管塞，振摇1min，解吸30min。解吸液供测定。若浓度超过测定范围，用二硫化碳稀释后测定，计算时乘以稀释倍数。2.标准曲线的绘制：加10ml二硫化碳于比色管中，用微量注射器准确分别加入10l 苯、甲苯、二甲苯（在20，1l 苯、甲苯、邻二甲苯、间二甲苯、对二甲苯分别为0.8787mg、0.8669mg、0.8802mg、0.8642mg、0.8611mg），为标准溶液4。再将此标准液依次4倍稀释成下列标准系列。进样1.0l，测定各标准管。以峰面积分别对苯、甲苯及二甲苯浓度(g/ml)绘制标准曲线。,MOE Ke
7、y Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,3.样品测定：用测定标准系列的操作条件测定样品和空白对照的解吸液；测得的样品峰面积值减去空白对照峰面积值后，由标准曲线得苯、甲苯、二甲苯的浓度(g/ml)。,MOE Key Laboratory of
8、 Environmental&Health,Institute of Environmental Medicine,School of Public Health,【计 算】1.按式（1）将采样体积换算成标准采样体积：（1）式中：Vo：标准采样体积（L）；Vt：采样体积（L）；t：采样点的温度（）；P：采样点的大气压，kPa。2.按式（2）计算空气中苯、甲苯、二甲苯的浓度。（2）式中：C：空气中苯、甲苯、二甲苯的浓度，mg/m3；c1,c2：测得前后段解吸液中苯、甲苯、二甲苯的浓度，g/ml；v：解吸液的体积，ml；Vo：标准采样体积，L；D：解吸效率，%。,MOE Key Laborator
9、y of Environmental&Health,Institute of Environmental Medicine,School of Public Health,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,MOE Key
10、Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,MOE Key Laboratory of Environmental&Health,Institute of Environmental Medicine,School of Public Health,【思考题】1.如何通过标准物质定性分析？2.如果二甲苯的三个峰没有分开，如何才能得到分离效果较好的峰？3.气相色谱仪有几个部分组成？4.假定我们的样品是大气或者工厂生产车间的样本，请说明该处气体达到何种国家标准值？,
