HOLD-UP TIME MEASUREMENTS FOR HIGH-SPEED GAS-CHROMATOGRAPHY

Hold-up time determination for high-speed gas chromatography is an important but difficult measurement, as hold-up times may be only a few seconds or less. We describe a technique where production of methane from thermal cracking of higher molecular weight compounds in an electrically heated cold trap inlet system can be used for an accurate and reliable measure for hold-up time. Hold-up time measurements from this technique are compared with values obtained from direct methane injections and from analysis of retention time data of a homologous series.