An empirical equation for the calculation of retention time with extrapolation of temperature in gas chromatography

Abstract

SummaryAn empirical equation is proposed to accurately correlate isothermal data over a wide range of temperature. With the equation in k -A* + B*/T "~ the retention times of different solutes tested on OV-101, SE-54 and PEG 20M capillary columns have been achieved even when 2 is assigned a constant value of 1.7. Comparison with i n k -A + BIT and in k -c + d / T + h/T 2, shows that the proposed equation is of higher accuracy and is applicable to extrapolation calculation, especially from data at high temperature to those at low temperature. Parameters A* and B* as well as A and B are also discussed. The hnear correlation of A* and B* is weaker than that of A and B.

Prediction of GC retention values under various column temperature conditions from temperature programmed data

“…(1) is the calculated value of holdup time, tR, e(1) and tR, c (1) are the retention times for determination and re-calculation values at temperature mode "1", respectively. In order to correlate retention time with temperature accurately, and empirical equation [20] has been suggested as follows,…”

Regression against Temperature of Gas–Liquid Chromatography Retention Factors. Van’t Hoff Analysis

“…The dependence of retention factors k on temperature is often approximated with the two-parameter eq (Table , Model A). However, Chen et al . and other authors ,,, argue against the use of Model A particularly for extended temperature ranges due to clearly identifiable systematic errors.…”

“…Haidacher et al 39 Hearn and Zhao 40 Guillarme et al 41 Rowe et al 42 The dependence of retention factors k on temperature is often approximated with the two-parameter eq (Table 1, Model A). However, Chen et al 44 and other authors 19,20,29,45 argue against the use of Model A particularly for extended temperature ranges due to clearly identifiable systematic errors. In the numerous cases in which there is a linear relationship between ln k and 1/T, as often observed in simple chromatographic systems, a correct determination of Δ solv H°a nd Δ solv S°involves the measurement of the retention factors of the solute in a relatively limited temperature interval (e.g., 30 K 35,36 ).…”