Performance test of portable analyzers for total hydrocarbons (THC) through a cross-calibration against gas chromatograph

The analytical performance of portable total hydrocarbon (THC) analyzers was investigated for the determination of atmospheric hydrocarbons (e.g., propane, benzene, toluene, and p-xylene). To evaluate the reliability of the portable system, experiments were initially conducted by examining their relative calibration patterns with gas chromatograph (GC). Secondly, two different types of THC analyzers (e.g., Micro-FID and TVA-1000) were inter-compared using the standard gases with varying concentration levels. Lastly, the performance of Micro-FID was tested against standard gases of varying compositions under different instrumental settings. The sensitivity of the GC–FID system, while gradually decreasing with the extension of calibration range, showed approximately 24% of reduction with each 10-fold increase in the maximum quantifiable mass of analyte. The relative performance of the THC analyzers also contrasted sharply between different systems to show gradual variations in experimental bias: the experimental bias of Micro-FID decreased with increasing analyte concentration, but the case was reversed for TVA-1000. To acquire reliable data from the THC analyzers, the setup of the response factor should also be considered in conjunction with the concentration level and composition of samples. In conclusion, because portable analytical systems are affected sensitively by various experimental variables, one can achieve improved performance of such systems by carefully evaluating the variability involved in their applications.