Precise gas chromatographic determination of hydrogen and C/sub 1/ to C/sub 5/ hydrocarbons by the simultaneous use of columns in parallel

Description/Abstract

Universal-Matthey Products Ltd., England, developed an accurate quantitative method for analyzing hydrogen and C/sub 1/-C/sub 5/ simultaneously by splitting the carrier gas flow through parallel columns in one chromatograph to flame ionization and katharometer detectors. The columns to the katharometer separate the hydrogen and retain the hydrocarbons until backflushed, while the ones to the flame ionization detector separate the hydrocarbons and backflush the compounds eluted after n-pentane. The lengths of the columns are sized so that hydrogen is eluted from Column 2 ahead of methane from Column 4, an arrangement requiring only 1 data-handling system. The backflushing system is a variation of that proposed by D. R. Deans. No switching valves are used in the sample path; dead volume and sorption effects are eliminated. Application to a typical debutanizer overhead gas showed a maximum standard deviation of 50%. Precision compares favorably with data found in the literature.