盐析微萃取-气相色谱-质谱法测定实验室废水中7种苯系物

Salting out microextraction-gas chromatography-mass spectrometry for determination of seven monoaromatic hydrocarbons in laboratory wastewater

采用三氯甲烷作为萃取剂,氯化铵作为盐析剂,建立盐析微萃取-气相色谱-质谱法测定有机实验室废水中甲苯、乙苯、邻二甲苯、间二甲苯、对二甲苯、1,3,5-三甲苯、1,2,4-三甲苯的分析方法。当三氯甲烷用量为25μL,氯化铵用量为0.2 g,5 000 r/min下离心分离5 min时,1 m L水样中的苯系物能很好地被三氯甲烷萃取出来,富集倍数为40倍。色谱条件为:DB-5MS毛细管柱(30 m×0.25 mm×0.25μm),进样口温度220℃,载气为氦气,流量1 m L/min,分流比30∶1,进样量1μL,程序升温为:初始45℃保持3 min,3℃/min升温至70℃,再以30℃/min升至200℃保持2 min。质谱条件为:电子轰击离子源(EI),电子能量69.9e V,离子源温度240℃,四级杆温度150℃,电子倍增器电压1 741 V,采样深度1.5 mm,溶剂延迟3.5 min。在优化萃取和测定条件下,各组分的质量浓度在0.4~80μg/L内与峰面积线性关系良好,相关系数均大于0.992 5,各组分的检出限范围为0.01~0.5μg/L。对成都理工大学有机实验室中废水进行测定,能有效检出所含苯系物,同时做加标回收实验,回收率在92.92%~102.1%之间,相对标准偏差(n=5)在1.9%~4.5%之间,测定结果令人满意。

Salting out microextraction-gas chromatography-mass spectrometry method was developed by using chloroform as extractant and ammonium chloride as salting out agent to determine the amount of toluene, ethylbenzene, o-xylene,m-xylene, p-xylene, 1,3,5-trimethylbenzene and 1,2, 4 -trimethylbenzene in organic laboratory wastewater. When the chloroform was 25 μL,ammonium chloride was 0.2 g , and centrifugation time was 5 min under 5 000 r/min, 1 mL monoaromatic hydrocarbons in 1 mL water sample could be well extracted by chloroform with the enrichment factor being 40. Chromatographic conditions was as follows： DB-5MS capillary column （30 m× 0.25mm×0.25 μ m） was used, inlet temperature was 220 ℃,the carrier gas was helium with flow rate of 1 mL/min, the split ratio was 30：1, and the amount of sample injection was 1 μ L. The temperature program was： initial temperature of column was 45 ℃（3 min）,then increased to 7 0℃ at 3℃/min, and increased to 200℃ at 30℃/min,and keeping for 2min. The condition of mass spectrometry was as follows：ion source was electron impact with electron energy of 69.9 eV, ion source temperature was 240 ℃,quadrupole temperature was 150 ℃,electron multiplier voltage was 1741 V, sampling depth was 1.5 mm and solvent delay was 3.5min. Under the optimized extraction and determination condition, the concentration of each component in the range of 0.4-80μ g/L had fine linear relationship with peak area, and the correlation coefficients were greater than 0.992 5. The detection limit of each component were 0.01 -0.5 μ g/ L. The monoaromatic hydrocarbons in wastewater from organic laboratory of Chengdu University of Technology could be measured effectively. At the same time, the recovery experiments were conducted, the recovery rate and relative standard deviation were in the rage of 92.92%-102.1% and 1.9%-45.% respectively. The results were satisfactory.