Real-Time Transformer Oil Polychlorinated Biphenyl Sensor

Polychlorinated biphenyls (PCBs) remain a significant environmental threat even though manufacturing of PCBs was discontinued 30 years ago. PCBs are toxic and suspected to be carcinogenic to humans and therefore are monitored carefully. Because of the chemical and thermal stability of PCBs in the environment and the continued use of transformers containing these chemicals, very specific regulations are in place that require the quantification of PCBs in all transformer oil. The Toxic Substance Control Act has mandated that the concentration of PCBs in transformer oil be less than 50 parts per million. Analysis of PCB concentration is currently performed by ASTM standards in an analytical laboratory using gas chromatography. This type of analysis is time consuming and costly. In addition, for this off-site analysis, oil must be removed from the transformer, which potentially exposes workers and the environment to PCBs. There is an opportunity to develop a portable real-time sensor that can be used on-site to quantify which PCBs are present and in what concentration. In this Phase I SBIR project, Raman spectroscopy and multivariate analysis will be used to create a rapid in situ sensor capable of simultaneous detection of PCB concentration and composition within transformer oil. A matrix of Raman spectra corresponding to specific concentrations and specific mixtures of PCBs will be collected and compiled using multivariate analysis software. Raman spectra will be collected using fiber optics and a submersible Raman probe. This will allow collection of Raman spectra without removing oil from the transformer. Chemometric models then will be created that will allow the determination of PCB concentration and type based on a single Raman spectrum of an unknown transformer oil sample. Eltron Research, Inc. has extensive experience in the development of sensors based on this technology. Once developed this type of sensor will easily be modified for rapid detection of PCBs in a variety of different media. The final product of this project will be a real-time sensor that is cost effective, portable, user friendly, and, most importantly, will prevent the hazardous removal and transportation of contaminated transformer oil for PCB analysis.