| Abstract: | GC, including capillary GC, is rather inflexible, if a certain column length and stationary phase has been fixed for a given analytical problem. If the sample composition changes, one often has to change the column length and/or stationary phase, at least when something like optimum analytical conditions are needed. Temperature changes (or heating rates) can change the selectivity of a given column only within very limited ranges, due to the exponential effect of temperature on retention time. By serial coupling two chemically different capillaries, each run at another temperature, even the slightest changes of these two temperature values have a dramatic effect on the selectivity of the system for polar substances. We call this technique the SECAT mode of GC. Results are reported as retention index shifts, dependent on SECAT temperature data. This technique can in future easily be automated, thus enabling the analyst, for polar sample analysis, to adjust a given chroma-tographic system to his specific sample composition without touching the instrument. |
