Sampling and analysis of polychlorinated biphenyls in indoor air by sorbent enrichment followed by headspace solid-phase microextraction and gas chromatography-tandem mass spectrometry

In this study, a combination of solid-phase extraction (SPE) and solid-phase microextraction (SPME) techniques has been used to determine polychlorinated biphenyls (PCBs) in air. Using a vacuum pump, a known volume of air was pulled through a porous polymer (Tenax TA) where the target analytes were retained and then headspace SPME was carried out. The quantification was performed using gas chromatography coupled to tandem mass spectrometry. Certain factors, such as temperature and the addition of solvents to the adsorbent, were found to be very important for the transfer of the target PCBs from the Tenax to the SPME fiber. Some of these factors were studied using an experimental design strategy. Performance of the method was evaluated demonstrating that external calibration, which does not require performing the complete sampling process, was suitable. The coefficients of determination were calculated and a lack-of-fit test was run within the calibration data, demonstrating linearity of the method. Repeatability was found adequate (RSD ≤ 12%). Limits of detection (LODs) were found below 0.100 ng/m3 when only 2.5 m3 air were sampled. These LODs were low enough to check for harmful levels of PCBs in indoor air, and are well below the most restrictive limits established by countries regulations. In addition, more sensitivity could be attained by increasing the volume of air sampled (decrease in retention efficiency was not detected for sample volumes up to 25 m3), and/or extending the extraction time in the SPME step.