Portable gas chromatograph calibration with gases of varying viscosities.

The quantitative analysis of gas mixtures with gas chromatography is based on the calibration with certified standards and the determination of a response relationship for each species by regression analysis. The conventional assumption of a constant amount-of-substance injected onto the column, the sample size, for all standards analyzed represents one of the largest sources of uncertainies in this analysis technique. For systems using time-based microinjectors, the sample size injected onto the column is determined by the opening time of a pneumatically actuated microvalve and therefore depends upon the gas velocity developed in the injector's microchannel.