Gas chromatography-vacuum ultraviolet detection for classification and speciation of polychlorinated biphenyls in industrial mixtures.

Polychlorinated biphenyls (PCBs) are a group of synthetic chlorinated compounds that have been widely used as dielectric fluids in capacitors and transformers. Due to their toxicity, persistence, and bioaccumulation in the food chain, PCBs are an environmental concern and among the most analyzed compounds in environmental analysis. The most common analytical methods for analysis of PCBs are based on gas chromatography-electron capture detection (GC-ECD) and gas chromatography-mass spectrometry (GC-MS). However, the number of possible congeners (209), similarities of physical and chemical properties, and complexity of sample matrices make it difficult to distinguish and accurately speciate PCB congeners using existing methods. This study presents a new method using gas chromatography with vacuum ultraviolet detection (GC-VUV), which offers absorption detection in the range of 120-240nm, where all chemical species have absorption. The VUV absorption spectra for all 209 PCB congeners were collected and shown to be differentiable. The capability of VUV data analysis software for deconvolution of co-eluting signals was also demonstrated. An automated time interval deconvolution (TID) procedure was applied to rapidly speciate individual PCBs, as well as classify commercial Aroclor mixtures based on their degree of chlorination. The data showed excellent agreement between the stated nominal and determined degrees of chlorination (less than 1% deviation for highly chlorinated mixtures). GC-VUV was verified to provide excellent specificity, high sensitivity (100-150pg limit of detection), and fast data acquisition for this application.