CALCULATION OF PROGRAMMED TEMPERATURE RETENTION INDEXES .2. OPTIMIZATION OF TEMPERATURE-DEPENDENCE CALCULATION

Programmed Temperature Retention Indices (PTRI) of several solutes on four packed columns coated with stationary phases covering a range of polarities have been estimated for sixteen temperature programs by exploiting isothermal retention data obtained at 70-180-degrees-C. PTRI calculations have been carried out by interpolating the retention temperatures calculated according to Curvers et al. from the graphs of retention index against column temperature, matched according to polynomials of grade 1 to 3 and by hyperbolic fitting. PTRIs by the van den Doole & Kratz equation and by cubic splines have also been computed. Comparison is made of these PTRIs with those calculated from cubic splines of the measured retention temperatures throughout the various temperature programs and the retention index deviations in terms of variance and relative error are explored. The smallest variance are found for the less polar stationary phases, PS-255 and OV-105; the biggest variance values are found for OV-275. Data are given showing that about 95 % of the determinations of PTRIs on the low polarity stationary phases show deviations of not greater than 2 %.