Monitoring Method of Polar VOCs in Industrial Wastewater Using Ultrasound Coupled HS-SPME

A novel system for the continuous, on-site monitoring of polar organic compounds in industrial wastewater is presented. Technically the system utilizes an ultrasound coupled autosampler, headspace solid-phase microextraction (HS-SPME), and a GC/FID for the automatic in situ detection and quantification of polar volatile organic compounds (VOCs). The system was first extensively validated in the laboratory, and then brought to a wastewater treatment plant for further experimentations. In the field experiments, seven VOCs have been successfully detected and quantified using this system. Experimental data have shown that the system exhibits a good linearity with a relative standard deviation (RSD) to the calibration smaller than 15%, a recovery rate above 90%, a precision between 6.5% and 11.5%, and the method detection limit (MDL) between 3.19ppb and 7.57ppb. These data have further demonstrated that the use of ultrasound significantly reduces the time for the HS-SPME fiber to reach equilibrium and, subsequently, shortens the sampling time. In addition, an onsite, automatic station has been constructed to continuously monitor and record the concentration levels of VOCs in the wastewater.