A thermoelectrically cooled surface-enhanced Raman spectrometer sensor system and method for monitoring of volatile organic compounds in gas, liquid, and soil environments. The sensor system comprises a means for providing an inert gas, a thermal desorption tube containing an adsorbate, and a sample chamber with a SERS structure. For liquid and soil environments, the sensor system also comprises a manifold having a semipermeable membrane for separating moisture from an analyte. An optical module mounted to the sample chamber directs an optical excitation signal for irradiating the SERS structure and receives a SERS optical emissions signal. Such optical emissions signal may be detected by a spectroanalysis system and correlated to a particular analyte by a control processor, which generates an alert signal containing a message that the presence of analyte has been detected. The control processor may also activate warning device, such as an audible siren or a visual alarm.