Ebrahimzadeh Homeira, Yamini Yadollah, Kamarei Fahimeh
Department of Chemistry, Shahid Beheshti University, Tehran, Iran.
Talanta. 2009 Oct 15;79(5):1472-7. doi: 10.1016/j.talanta.2009.06.022. Epub 2009 Jun 16.
Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-flame ionization detector (GC-FID) was developed for preconcentration and determination of some nitroaromatic compounds in wastewater samples. The effects of different variables on the extraction efficiency were studied simultaneously using experimental design. The variables of interest in the DLLME process were extraction and disperser solvent volumes, salt effect, sample volume, extraction temperature and extraction time. A Plackett-Burman design was performed for screening of variables in order to determine the significant variables affecting the extraction efficiency. Then, the significant factors were optimized by using a central composite design (CCD) and the response surface equations were derived. The optimum experimental conditions found from this statistical evaluation included: sample volume, 9 mL; extraction solvent (CCl(4)) volume, 20 microL; disperser solvent (methanol) volume, 0.75 mL; sodium chloride concentration, 3% (w/v); extraction temperature, 20 degrees C and extraction time, 2 min. Under the optimum conditions, the preconcentration factors were between 202 and 314. Limit of detections (LODs) ranged from 0.09 microg L(-1) (for 2-nitrotoluene) to 0.5 microg L(-1) (for 2,4-dinitrotoluene). Linear dynamic ranges (LDRs) of 0.5-300 and 1-400 microg L(-1) were obtained for mononitrotoluenes (MNTs) and dinitrotoluenes (DNTs), respectively. Performance of the present method was evaluated for extraction and determination of nitroaromatic compounds in wastewater samples in the range of microgram per liter and satisfactory results were obtained (RSDs<10.1%).
建立了分散液液微萃取（DLLME）结合气相色谱 - 火焰离子化检测器（GC - FID）的方法，用于废水样品中某些硝基芳香族化合物的预富集和测定。采用实验设计同时研究了不同变量对萃取效率的影响。DLLME过程中感兴趣的变量有萃取剂和分散剂的体积、盐效应、样品体积、萃取温度和萃取时间。采用Plackett - Burman设计对变量进行筛选，以确定影响萃取效率的显著变量。然后，通过中心复合设计（CCD）对显著因素进行优化，并推导响应面方程。通过该统计评估得出的最佳实验条件包括：样品体积9 mL；萃取溶剂（CCl₄）体积20 μL；分散剂溶剂（甲醇）体积0.75 mL；氯化钠浓度3%（w/v）；萃取温度20℃；萃取时间2 min。在最佳条件下，预富集因子在202至314之间。检测限（LOD）范围为0.09 μg L⁻¹（对于2 - 硝基甲苯）至0.5 μg L⁻¹（对于2,4 - 二硝基甲苯）。单硝基甲苯（MNTs）和二硝基甲苯（DNTs）的线性动态范围（LDRs）分别为0.5 - 300 μg L⁻¹和1 - 400 μg L⁻¹。对本方法用于测定微克每升范围内废水样品中硝基芳香族化合物的萃取性能进行了评估，获得了满意的结果（相对标准偏差<10.1%）。
