Benzene, toluene, ethylbenzene and xylenes are referred to simply as BTEX; BTEX is one of the most common and dangerous groups of environmental air pollutants. In the original BTEX quantitative standard analysis method, it is often limited by the complexity of sampling and sample preparation equipment and budget requirements. Packaging air samples with a 20ml headspace vial is a convenient way to package them. Based on the original SPME method, this way represents a simpler quantitative analysis scheme, but solid-phase extraction requires a complex calibration procedure. The purpose of this study is to develop a simpler, lower-budget and more accurate analysis of BTEX quantitatively. Combined with SPME and GC-MS, the field air is sampled directly using a standard 20ml headspace vial in ambient air; The BTEX is calibrated and quantified using GC-MS technology. To avoid the challenge of obtaining and handling "zero" air, use standard added and inherently contaminated laboratory air to determine the slope factor for external standard calibration. Seal the standard 20ml headspace vial in advance in the laboratory; And sit in the lab for 24 hours.
The PDMS fiber in the sample air provides higher accuracy during calibration, and the use of Carbonen/PDMS fiber can reduce the detection limit of benzene and toluene. In order to provide sufficient accuracy, the use of 20mL headspace vials requires tripartite sampling and analysis. This method was successfully applied to the analysis of 108 ambient air samples in Almaty, Kazakhstan. The average concentrations of benzene, toluene, ethylbenzene and xylene were 53, 57, 11 and 14 μgm (-3) respectively, by taking three samples of the air samples of 20ml headspace vial. This quantitative analysis method can still be modified to further quantify the wider range of volatile organic compounds in the air. In addition, 20ml headspace vial applications can be automated.