The achievement of reproducible temperature prodgrammed retention indices in gas chromatography when using different columns and detectors

Summary

It has been found that the ratio$\frac{{r \cdot t_0 }}{\beta }$, where r is the heating rate, t₀ is the gas hold-up time of the column and β is the phase ratio of the column used, is a most explicit and convenient parameter in linear temperatur-programmed gas chromatography for reproducing temperature-programmed retention indices, I_TP. For two columns of different sizes (length, inner diamter), working under different heating rates with the same or different carrier gases at different gas flow-rates, as long as the initial oven temperature, T₀, phase ratio, β, and their r·t₀/β ratios are kept unchanged, the I_TP value of a solute can be reproduced within 1–2 i.u. on either OV-101 or PEG-20M columns. When a combined gas chromatography-mass spectrometry technique is used applying vacuum at the column outlet reduces t₀. Nevertheless, r·t₀/β can still be kept unchanged by a proper choice of the oven heating rate, and thus a total ion chromatogram (TIC), quite similar to the corresponding gas chromatogram in shape, can be obtained.