The Research On Detection Method Of Benzidine And 4-fluoroaniline In Water By Enrichment And Liquid Chromatography

Benzidine and 4-fluoroaniline are important intermediates of synthetic dyes.They have potential carcinogenic effects.Benzidine and 4-fluoroaniline mainly presents in the industrial dye production wastewater.It is significant to precise scientific monitor the emission of benzidine and 4-fluoroaniline in the dye wastewater in order to control the dye pollution and maintain the ecological balance.This paper have systematically studied on extraction and determination techniques for benzidine and 4-fluoroaniline in water.The analysis method of Solid phase extraction and liquid chromatography with fluorescence detection were developed for determining benzidine and 4-fluoroaniline in water.The primary coverage contain the following four aspects:Part 1:Review of environmental characteristics of benzidine and 4-fluoroaniline as well as the analysis method,mainly including structure,physical and chemical properties,toxicity,pollution treatment technology and the domestic and foreign currently benzidine and 4-fluoroaniline detection methods reported in the literature.The advantages and disadvantages of the existing standards of benzidine and 4-fluoro aniline at home and abroad are compared.Part 2:The best pre-treatment conditions of benzidine and 4-fluoroaniline were optimized.Solid phase extraction(SPE)was used to investigate the extraction effect of different types of solid phase extraction columns on benzidine and 4-fluoroaniline.It was found that PCX mixed cation exchange solid-phase extraction column can simultaneously enrich benzidine and 4-fluoroaniline.The volume of sample,sample speed,leaching and elution conditions were optimized to determine the sample size for 150 m L,at a speed of 2?3mL/min through the SPE columns,target compounds with 3% acetic acid water,add 8mL of methanol eluting impurity and elution with 7mL5% ammonia methanol.Influence of different pH to benzidine and 4-fluoroaniline was compared,and it was determined that recoveries were best when pH is 6?10.The suspended substance has adsorption effect on benzidine and 4-fluoroaniline,and the adsorption of suspended substance is reduced by adjusting the pH.Part 3:The liquid-chromatography with fluorescence detection wavelength programming for determination of benzidine and 4-fluoroaniline in environmental water was developed.The optimum chromatographic separation conditions were determined by optimizing the best detection wavelength,elution mode and column temperature.The linear range and detection limit of benzidine and 4-fluoroaniline were studied by external standard quantitative determination.The results indicated that benzidine and 4-fluoroaniline had a good linear relationship at 1.0~100 μg/L and 2.0~200 μg/L with a correlation coefficient of 0.9999 and 0.9998,and the method detection limits(MDL)were 0.0094 μg/L and 0.014 μg/L,respectively.The RSD of precisions were 2.1%~7.6%,the recoveries of practical samples were within 75.2%~105%.The stability of benzidine and 4-fluoroaniline in three different water was studied.The results showed that the water samples containing benzidine and 4-fluoroaniline could be stabilized 5 days at 0℃?4℃ under the refrigeration in dark.Part 4: The samples from tap water,drinking water sources,sewage treatment plants and dyeing as well as finishing wastewater treatment plants were analyzed.The results showed that 4-fluoroaniline and benzidine in tap water,drinking water sources and sewage treatment plants were not detected,and the quality could achieve the water quality standard《Standards for Surface Water Quality》(GB 3838-2002).And the water quality of some printing and dyeing factories could meet the requirements of China’s mandatory standard《Basic Safety Technical Specification for National Textile Products》(GB18401-2003).The concentration of benzidine in the individual dye manufacturer exceeds the standard limit.