INDEPENDENTLY TEMPERATURE-PROGRAMMED UNCOATED PRECOLUMN - A CONCEPT FOR IMPROVED SAMPLE INTRODUCTION IN CAPILLARY GC

In this paper, a GC sample introduction technique is described in whic h an uncoated precolumn and the analytical capillary column are indivi dually temperature programmed. The influence of different rates of tem perature programming of the retention gap on band broadening of a seri es of n-alkanes has been investigated for different lengths of the pre column. It is shown that extra column band broadening of high boiling solutes is reduced when the temperature of the precolumn is ramped at a faster rate than the analytical column. This benefit is particularly pronounced when long retention gaps are employed. The technique exten ds the useful lifetime of the analytical column when complex real-worl d samples with a wide volatility range are analyzed. This is due to th e fact that the final temperature of the precolumn can be kept below t he final temperature of the analytical column. Thus, the column is not contaminated with high boiling non-elutable solutes.