Optimizing capillary column backflush to improve cycle time and reduce column contamination

Abstract

Interest in decreasing cycle times in capillary GC analyses has driven much of the instrumental developments of the last decade. Recent developments in GC instrumentation now make it reasonable to consider backflushing capillary columns on a routine basis. Significant reduction in analysis and total cycle times (typically 15-50% depending on the application) are readily achieved for analyses that currently require an extended temperature program and bakeout period to remove retained sample components and column contaminants. Setup and optimization of backflush conditions are relatively straight forward as long as some basic concepts are well understood. The parameters affecting capillary column backflushing are described. Examples are shown that help visualize what happens during backflush. The relationship between oven ramp rate and flow turns out to be an important variable that dictates minimum backflush times in temperature programmed CGC. Backflush times corresponding to 2-5 void volumes in the reversed direction are usually sufficient for backflushing, if performed after each temperature programmed run.

Evaluation of fast enantioselective multidimensional gas chromatography methods for monoterpenic compounds: Authenticity control of Australian tea tree oil

“…Overall, the proposed GC-eGC method achieved interference-free enantioseparation of the analytes of interest in less than 25 min. This is much shorter than the reported two-column coupled system (>30 min; but with co-elution between p-cymene and (+)-limonene) [15] and a dual oven GC-eGC approach (>91 min), in addition to providing reduced chemical background and better reproducibility (presumably due to backflushing of the 1 D column) [10,16].…”

Fast Transmethylation of Total Lipids in Dried Blood by Microwave Irradiation and its Application to a Population Study

“…This makes it necessary to purge the column for an extended period of time after each run to avoid interference with subsequent data acquisitions. This problem could be minimized by the newly developed technology of capillary column backflush [36] that significantly reduces the bakeout time during our pilot experiments.…”

Gas chromatographic retention in uncoated fused silica capillaries

“…An evolving, relatively new application of uncoated capillaries is in capillary column backflushing [9,10]. In capillary column backflushing, the flow through a column is reversed after elution of the last component of interest to remove highly retained sample components so that the run time can be shortened and the column can be kept clean.…”