Effects of injection volume change on gas chromatographic sensitivity determined with two contrasting calibration approaches for volatile organic compounds

In this study, the effects of injection volume change on gas chromatographic detection properties have been evaluated using gas-phase standards containing three aromatic volatile organic compounds (VOC): benzene, toluene, and xylene (commonly called BTX). To examine such effects on GC sensitivity, a series of calibration data sets were obtained using standards of three concentration values (3, 6, and 10 ppm) at each of five selected injection volumes (20 to 1000 microL). The results were initially examined in terms of the fixed standard volume (FSV) approach to allow the direct comparison of calibration patterns between different injection volumes. Identical data sets were then re-organized so that the calibration data could also be compared across variable injection volumes for a given standard concentration (at all three concentrations), i.e. by the fixed standard concentration (FSC) approach. The results of our comparative analysis between the FSV and the FSC approaches indicate that the calibration patterns of VOC are highly sensitive to changes in injection volume or injection-related conditions. It is thus suggested that the former approach is more reasonable for reducing uncertainties associated with the GC-based quantification of atmospheric pollutants.