Simultaneous Determination of Pyridine, Aniline and Nitrobenzene in Printing and Dyeing Wastewater by Headspace Gas Chromatography-Mass Spectrometry

Pyridine, aniline, and nitrobenzene are important chemical raw materials with low boiling point and strong polarity. They are highly susceptible to enter environmental water and cause pollution. Printing and dyeing wastewater with a complex matrix contains various carcinogenic nitrogen-containing organic pollutants, such as pyridine, aniline, and nitrobenzene. Printing and dyeing wastewater discharging into the environment is harmful to human health through the food chain. The simultaneous detection method of pyridine, aniline, and nitrobenzene in environmental water is necessary.

To establish an analytical method based on headspace gas chromatography-mass spectrometry for the simultaneous determination of pyridine, aniline, and nitrobenzene in water.

The contents of pyridine, aniline, and nitrobenzene in the effluents from the wastewater treatment plants in the textile industry parks were detected and quantified by the external standard method with headspace gas chromatography-mass spectrometry method. Finally, the experiment conditions were optimized.

The results showed that the linear ranges of pyridine and aniline were between 1.00µg/L and 30.0µg/L, and nitrobenzene was in the mass concentration range of 0.50-15.0µg/L, with the correlation coefficient above 0.992. The limits of detection were 0.15-0.93µg/L. The concentrations of pyridine, aniline and nitrobenzene in the effluents of the wastewater treatment plant in the textile industry parks were detected from 1.10µg/L to 1.13µg/L, from 1.71µg/L to 5.36µg/L and from ND to 0.19µg/L, respectively. The average recoveries of samples from laboratory blanks and wastewater treatment plant effluents at three levels of addition were 73.6% to 105.8% and 67.2% to 89.9%, respectively, with relative standard deviations of 5.9% to 14.2% (n=8) and 2.2% to 11.5% (n=6). The process and conditions of headspace are summarized as follows: 10.0mL of sample was placed into a 20mL headspace bottle containing 4.0g Na₂CO₃, and then 50µL methanol was added; the equilibration time of the headspace sampler was 60 min, and the equilibrium temperature was 80℃.

Some measures are conductive to improving the sensitivity of the method, such as addition of methanol and sodium carbonate, and increasing the sample equilibrium temperature, in order to reduce the dissolved concentrations of the targets in the water and improve the precipitation effect of the targets. This method improves the detection efficiency, and is of significance for the simultaneous monitoring of pyridine, aniline, and nitrobenzene in printing and dyeing wastewater.