Determination Of Nitroanilines In Environment Samples By High Performance Liquid Chromatography

Nitroanilines such as2-nitroaniline (2-NA),3-nitroaniline (3-NA),4-nitroaniline (4-NA) and2,4-dinitroaniline (2,4-DINA) are commonly encountered organic contaminants in environmental.These nitroanilines are carcinogenic and non-or hardly biodegradable under aerobic conditions which will make them form a cumulative effect in the environmental water systerm. Hence, in the study, these four nitroanilines were analyzed. According to their characteristics, HPLC-UV was selected as detector. On extraction method selection, soxhlet extraction and dispersive liquid phase microextraction were used as the extract methods in soil and aqueous samples, respectively. Evaluating the factors to assess theirs applications for the extraction and analysis of nitroanilines. The main content of this paper is summarized as follows:(1) A soxhlet extraction-liquid chromatography-ultravioletdetection method (SE-HPLC-UV vis) was developed for the determination of four nitroaniline isomers in soil samples. Results showed that under the conditions of Hypersil BDS C18column, mobile phase=55%(volume) methanol, flow rate=1.0mL/min and the wavelength of ultraviolet detection=230nm, four nitroaniline isomers could be separated well whthin10minutes. As for the soxhlet extraction, present study reavealed that using methylene chloride as the extractant could greatly reduce the backgrand interference in HPLC-UV vis system. And according to the single-factor test, the best extraction efficiency could be achieved by using following extract conditions:temperature=55℃, time=8h, solvent volume=60mL. Further experiments showed that the method had good linear relationship, low detection limit, high recovery rates (>90%) and good precision (RSD ranged from1.85%to4.07%).(2) An analytical method, dispersive liquid-liquid microextraction-liquid chromatography, was developed for the determination of four nitroanilines in water sample. Several factors, influencing the performance of dispersive liquid-liquid microextraction (DLLME) such as extractant type and volume, disperser type and volume, pH and ionic strength, were studied and optimized using single-factor experiments. The optimized dispersive liquid-liquid microextraction conditions were as follows:the volume of extractant was75μL(CCl3), the volume of dispersive solvent(methanol) was lmL, and the salt addition was3%(w/v). Under the optimal conditions, the linear range of the proposed method was wide,R2>0.9991,and the limit of detection was0.08～0.26μg/L at S/N=3. The extraction recovery ranged from64.29%to108.89%,with relative standard deviation(RSD) between1.45%～5.64%(n=6). Meanwhile, the determination of nitroanilines was not interfered by matrix effect. The developed method was simple and fast for the nitroanilines determination in water sample.(3) A modified dispersive liquid phase microextraction named as ionic liquid-based ultrasonic-assisted temperature controlled dispersive liquid phase microextraction was studied for the extraction of nitroanilines from aqueous samples, before liquid chromatographic analysis with ultraviolet detection (HPLC-UV). Ultrasonic was applied to accelerate the extraction equilibrium, and temperature promote the dispersing of ionic liquid into the solution, increasing the chance of the analytes extracted into ionic liquid phase. The optimal experimental conditions obtained from this statistical evaluation included:extraction solvent,1-buryl-3-methylimidazolium hexafluorophosphate([BMIM][PF6]); extraction solvent volume,100μL; extraction time,5min; centrifugation time,5min; bath temperature,60℃; and salt addition,2%(w/v). Under the optimal conditions, the spiked recovery for each analyte was more than86.46%. The precisions of the proposed method were varied from1.14%to3.38%(RSD). All the analytes exhibited good linearity with correlation coefficients(R2) ranging from0.9979to0.9990. The limits of detection for all target analytes were ranged from0.69to1.82μg/L (S/N=3). This method has been also successfully applied to analyze the real water samples at two different spiked concentrations and excellent results were obtained.