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    活性炭吸附分离-气相色谱-质谱法测定室内空气中二硫化碳的含量

    GC-MS Determination of CS2 in Indoor Air with Separation by Adsorption on Activated Carbon

    • 摘要: 移取2 μL二硫化碳标准储备溶液(二硫化碳的绝对质量小于4 μg)于动态稀释仪中,在选定的最佳条件下(吹扫流量为1 000 mL·min-1,吹扫时间为10 min)操作。仪器的出气口与活性炭吸附管连接,使空气中的二硫化碳被活性炭吸附。吹扫时间结束时,取下吸附管,移置于全自动热脱附仪中,按仪器工作条件操作,使二硫化碳解吸并引入气相色谱仪,在DB-5色谱柱(60 m×0.25 mm,0.25 μm)上按程序升温(温度区间为50~250℃)模式进行分离,按设定条件用质谱法测定二硫化碳的含量。用二硫化碳标准溶液系列绘制标准曲线,其线性范围在0.010~2.0 mg·L-1之间,检出限(3s)为0.007 μg。当采集体积为10 L时,其检出限为0.7 μg·m-3。用标准加入法进行回收试验,测得回收率在105%~110%之间,测定值的相对标准偏差(n=6)均小于4%。为检测吸附管中二硫化碳的稳定保持时间,取2 μL二硫化碳标准储备溶液9份,分别按上述条件吹扫,并吸附于9个吸附管中,在不同的时间测定其二硫化碳的含量。结果表明,吸附管中二硫化碳至少可保存72 h,在室温(23℃)和低温(-18℃)条件下,保存的吸附管中二硫化碳的测定结果之间无明显差异。

       

      Abstract: A dynamic dilution instrument, with its gas outlet connected with an activated carbon adsorption tube, was used for sampling of air and separation of CS2 from air by adsorption on activated carbon. An aliquot of 2 μL of CS2 standard reserve solution (absolute mass of CS2<4 μg) was introduced into the instrument and the air sample was collected under the optimum conditions (i.e., with flow-rate of 1 000 mL·min-1 and time of 10 min in sweeping). At the end of sweeping time, the adsorption tube was dis-connected and transferred to be thermo-desorption device in which the CS2 adsorbed on activated carbon was desorbed under the working condition of the desorption device and transferred to gas chromatograph to be separated on DB-5 chromatographic column (60 m×0.25 mm, 0.25 μm) under the mode of programed temperature elevation in the range between 50℃ to 250℃. Finally, CS2 separated by GC was determined by MS. Standard curve was prepared with standard solution of CS2 and analyzed by the same procedure described above. Linearity range of CS2 was found between 0.010 mg·L-1 to 2.0 mg·L-1 with detection limit (3s) of 0.007 μg or 0.7 μg·m-3 when 10 L of air sample were collected. Recovery was tested by the standard addition method giving value of recovery in the range of 105%-110%. Values of RSD (n=6) were found all less than 4%. To test for time of keeping of the CS2 adsorbed on activated carbon in the adsorption tube, 9 portions of 2 μL of CS2 standard reserve solution were taken and treated in the same way in the dynamic dilution instrument separately and 9 adsorption tubes with adsorbed CS2 were obtained and their contents of CS2 were determined by GC-MS after keeping for different times. It was shown that the concentration of CS2 in the adsorption tubes were kept stable at least for 72 h, and in further, the contents of CS2 determined in adsorption tubes kept under room temperature (23℃) and under low temperature (-18℃) showed no significant difference.

       

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