Development of a gas chromatography system coupled to a metal-oxide semiconductor (MOS) sensor, with compensation of the temperature effects on the column for the measurement of ethene
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Media type:
E-Article
Title:
Development of a gas chromatography system coupled to a metal-oxide semiconductor (MOS) sensor, with compensation of the temperature effects on the column for the measurement of ethene
Description:
Abstract. A possible way to reduce the size and complexity ofcommon gas chromatography (GC) systems is the economization of the columntemperature regulation system. To this end, a temperature compensationmethod was developed and validated on a benchtop GC-PDD (pulsed dischargedetector) with ethene. An in-house-developed algorithm correlates theretention index of a test gas to the retention index of a previouslyselected reference gas. To investigate further methods of cost reduction,commercial gas sensors were tested as cheap, sensitive, and versatiledetectors. Therefore, CO2 was chosen as a naturally occurring reference gas, while ethene was chosen as a maturity marker for climacteric fruits andhence as a test gas. A demonstrator, consisting of a simplesyringe injection system, a PLOT (porous layer open tubular) column boxed ina polystyrene-foam housing, a commercial MOS (metal-oxide semiconductor)sensor for the test gas, and a CO2-specific IR (infrared) sensor, wasused to set up a simple GC system and to apply this method ontest measurements. Sorption parameters for ethene and CO2 weredetermined via a van 't Hoff plot, where the entropy S was −11.982 J mol−1 K−1 ΔSEthene0 and 1.351 J mol−1 K−1 ΔSCarbondioxide0, and the enthalpy H was −20.622 kJ mol−1 ΔHEthene0 and −14.792 kJ mol−1 ΔHCarbondioxide0, respectively. Ethene (100 ppm) measurementsrevealed a system-specific correction term of 0.652 min. Furthermeasurements of ethene and interfering gases revealed a mean retention timefor ethene of 3.093 min; the mean predicted retention time is 3.099 min. Thedemonstrator was able to identify the test gas, ethene, as a function ofthe reference gas, CO2, in a first approach, without a column heatingsystem and in a gas mixture by applying a temperature compensation algorithmand a system-specific holdup time correction term.