Simple system for part-per-billion-level volatile organic compound analysis in groundwater and urban air

摘要: A simple device is described, capable of measuring reliably and reproducibly low levels (0.1 ppbv with a total analysis time approximately 40 min) volatile organic compounds (VOCs) in urban air the headspace groundwater. The VOCs were pre-concentrated onto small bed Tenax TA®, subsequently released by temperature-programmed thermal desorption (TPD). TPD profiles recorded solid-state sensor array. success method was based on well defined peak shape if absorbent sufficiently thin, linearity additivity appropriately transformed signals, use very stable array utilizing chromium-titanium oxide as material devices different electrode gaps dry carrier gas. Successful groundwater achieved diluting sample stream 1:4 (which prevented saturation adsorbent surface water) introducing purge at room temperature before removed excess water from hence stabilized baseline desorption). Principal components spectral decomposition (SD) methods used successfully for identification quantification mixtures. SD expressed measured trace elements sum number spectra. individual traces each characteristic spectrum thus derived could be further resolved fitting procedure because had form, which both width correlated boiling VOCs, varied according to functional type: phenols>aliphatics>alkyl-substituted benzenes.