The Vernier Mini GC Plus (Beaverton, OR) is a commercially available gas chromatograph (GC) that can separate, identify and quantitate volatile organic compounds (VOCs) contained in liquid or gaseous samples. VOC’s are important air pollutants, both indoors and outdoors and can have significant human health effects. The Mini GC Plus is small (1.3 kg, 2.7 L) and power-efficient (24 VDC, 60 W). Although intended for the educational market, we are evaluating it as a portable instrument for field screening of VOC’s. The Mini GC Plus contains an 11 meter capillary column (polydimethylsiloxane, inner diameter 0.53 mm, 30 ○C-160 ○C) with the capability of temperature programming. The mobile phase is ambient air, pulled through the column by a small pump (0.1 to 10.8 mL/min). Sample introduction by on-column injection of either liquid (&lt; 0.8 uL) or air containing organic vapors (&lt; 1 mL) is possible. Methods for directly identifying and quantitating compounds in a headspace mixture were developed and tested and found to be useful. A wide variety of samples were tested, including the head space from inks and markers, glues and cements, and personal care products. Retention time, peak area, and peak shape were characterized as a function of sample composition and injection size. Using calibration curves for individual compounds to quantify components in a mixture was successful. The effect of varying mobile phase flow rate between 0.27 and 11 mL/min on peak width was investigated, with peak capacity constant over the entire range. Statistically-based limits of detection (LOD) are presented for several liquid analytes. For example, butyl acetate has a limit of detection of 0.05 μL, toluene’s LOD is 0.08 μL, butyraldehyde’s LOD is 0.1 μL, and trichloroethylene’s LOD is about 0.08 μL. Preliminary data indicate that the Vernier Mini GC Plus may be a promising instrument for field studies of VOCs.

Evaluation of a portable gas chromatograph for environmental monitoring of pollutants

251st National Meeting (2016)

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