Evaluation of sources of irreproducibility of retention indices under programmed temperature gas chromatography conditions.

Retention index under the programmed temperature gas chromatography (PTGC) conditions (I) is widely accepted despite of its unsatisfactory reproducibility. Effects of heating rate (r), stationary liquid film thickness (d), inlet pressure (p), initial temperature (T) and polarity of stationary phase (s) on I reproducibility were studied in the present work. We found that excellent reproducibility and regularity of I values are obtainable at conditions of relatively low T and relatively high r and p, as well as use of quality thick-film column under an operation in a single-retention behavior region (i.