Review of Chemical Sensors for In-Situ Monitoring of Contaminants

This report presents a review of sensors and technologies that are capable of detecting and monitoring volatile organic compounds. The scope of this review was limited to those sensors that have the potential to be used in geologic environments for long-term monitoring applications. Four general categories of sensor technologies were reviewed: (1) chromatography and spectrometry; (2) electrochemical sensors; (3) mass sensors; and (4) optical sensors. Based on the review criteria set forth in this report, the most viable sensors for in-situ chemical sensing appear to be electrochemical sensors (specifically conductometric sensors), fiber-optic sensors, and surface-acoustic-wave sensors. However, very few chemical sensors have been successfully demonstrated in realtime, continuous, in-situ applications.