IMPROVEMENT OF THE REPRODUCIBILITY OF RETENTION INDEXES IN TEMPERATURE-PROGRAMMED GAS-LIQUID-CHROMATOGRAPHY - PART I - DB-1 COLUMN

For calculation of retention indices, retention data for the n-alkane reference series has to be measured. In most cases when we analyse sam ples having many components, it is not possible to mix the n-alkanes i nto the analysed sample. When we measured the retention times of n-alk anes from separate injections the calculated retention indices showed unacceptably large random deviations under programmed temperature oper ations. We describe a simple correction for the retention times of the reference n-alkanes to improve the reproducibility of the retention i ndices. For this correction the analysed samples must contain one n-al kane identical with a member of the reference series. Using the differ ences or ratios of the retention times of this one common n-alkane mea sured in the sample and measured separately, we can calculate normaliz ed sets of retention times of the n-alkane series. The retention indic es of the analysed solutes obtained by using these normalized retentio n times of the separately injected and measured reference series showe d a better reproducibility than without normalizing. (C) 1998 John Wil ey & Sons, Ltd.