Determination of benzene, toluene, ethylbenzene and xylenes by headspace spectrophotometry with an atomic absorption apparatus

In this study an atomic absorption spectrophotometer equipped with a selenium hollow-cathode lamp was used for analysis of BTEX (benzene, toluene, ethylbenzene and xylenes) in headspace of aqueous solutions. Initially effective factors on headspace such as volume of solution, stirring time, stirring speed, velocity of carrier gas, temperature, number of strippings, addition of salts and salt concentration were investigated and optimum conditions were selected. By addition of salt in different concentrations, different absorbances were obtained for headspace, therefore, binary mixtures of BTEX were analyzed with simultaneous equations. Obtained results agreed with actual amounts and repeatability was very good (RSD% <3). Correlation coefficients (r) for calibration curves were about 0.999. This proposed method is comparable with absorbance determination of solution with respect to correlation coefficient, linear dynamic range, limit of detection CLOD) and relative standard deviation (RSD), but this method is less susceptible to interferences and more selective.