Exposure to volatile organic chemicals (VOCs) in drinking water has been linked to a number of adverse health effects including cancer, liver, and kidney damage. However, the large number of potential contaminants and the cost and complexity of existing analytical methods limits the extent to which water quality is routinely characterized. This project focuses on the development and evaluation of an instrument for field analysis of VOCs in drinking water. The instrument will be based on an array of six polymer-coated surface-acoustic-wave microsensors. A test set consisting of dichloromethane, chloroform, 1,1,1-trichloroethane, perchloroethylene, and m-xylene will be used in a series of experiments designed to: 1) select and optimize the preconcentration system; 2) calibrate the instrument over the concentration range of 0.2-2 times the EPA Maximum Contaminant Level (MCL); and 3) compare results to those of a recognized laboratory. The primary goal is to develop a cost-effective alternative for on-site evaluation of VOCs in water.