Cantilever Based Gas Chromatography
Original Publication Date: 2002-Jan-12
Included in the Prior Art Database: 2003-Jun-20
One of the major drawbacks of electronic noses is their poor selectivity compared to chromatographic systems. While an electronic nose identifies analytes by the response of a sensor array, chromatographic systems separate complex mixtures in a carrier gas into fractions and detect the separated compounds of an analyte mixture via the component's elution time. A combination of a separation system, e.g. a gas chromatography (GC) column and the electronic nose for detection and additional identification the fractions, leads to a more powerful instrument. In this way, the main components of many samples, water and ethanol, can be separated, identified and quantified, or discarded via a bypass for more accurate measurements on the remaining constituents. Components with lower vapor pressures, often responsible for the odor of a sample are not longer dominated by the solvent. First measurements using this system show a separation of single components of a mixture. Beside the separation through the column, the sensor array responses show characteristic component-specific patterns. These patterns can be further evaluated to identify the component. In some cases, an electronic nose could substitute as mass spectrometer as a selective detector in GC. 1 The test setup shown in figure 1 consists of a digital mass flow controller providing a constant gas flow through the column. In front of the column, a six-terminal valve with a sample loop is installed. The sample loop can be filled with a syringe. When the valve is closed, the gas flow is redirected through the sample loop and passes the separation column. The electronic nose is connected to the outlet of the separation column as serves as a detector. The system is similar to a standard gas chromatograph. The system demonstrates the extended possibilities resulting from combining sensor array technology to chromatographic systems. An extention might be connection of an electronic tongue (sensor array working in liquids) to liquid chromatography technologies (FIA, HPLC (high pressure liquid chromatography, LPLC (low pressure liquid chromatography)).