Fast gas chromatography for industrial hygiene analysis and monitoring.

Industrial hygienists and chemists often rely on gas chromatography (GC) as the separation method during analysis of volatile organics. Although GC is an effective method of analysis, its usefulness is often limited by analysis times of several minutes or more. However, GC can be a much faster method of separation and analysis. If equipment and operating conditions are optimized for speed, many simple separations can be achieved in as little as a few seconds. Two fast GC systems were developed for use in industrial hygiene and environmental applications. One was designed for analysis of organic vapors, and the other for analysis of liquids. Both systems featured a gas cooled and resistively heated cold trap inlet that produced injection bands with widths of 15 to 25 ms. Separation was achieved with 2 to 5 meter lengths of 0.25 mm i.d. capillary column. Flame ionization detectors were used with the detector signal directed to a custom built, fast responding electrometer and a PC-based data system. This study shows that simple liquid mixtures of aromatics and aliphatics could often be separated in ten seconds or less. During replicate analyses, relative standard deviations for peak area were 1 to 10 per cent, and relative standard deviations for retention time were less than 1 per cent. Dilute solutions, with concentrations below 50 ug/ml, could not be analyzed due to the poor signal to noise ratios associated with fast responding electrometers. To validate the fast GC as a vapor monitoring system, a side-by-side comparison was made with conventional GC. Test atmospheres containing benzene, toluene and O-xylene were measured at various concentrations and at humidities ranging from 10% to 80%. At concentrations ranging from 100 ppm to 1 ppm or lower, the fast GC improved retention times by a factor of 50 relative to the conventional system with no loss of precision or accuracy. Changes in humidity were shown to have no effect on the performance of the instrument.PhDAnalytical chemistryEnvironmental scienceHealth and Environmental SciencesPublic healthPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/128436/2/9013979.pd