Problems and solutions to measure and maintain the high separation power of capillary columns (open tubular and packed type) at their optimum
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The separation number, TZ, is a practical measure of separation quality. TZ strongly depends on k. Sum of all TZ over the whole k-range divided by the uncorrected retention time tms of the last peak is a good measure of the separation power. The combined use of TZ and retention index data combines selectivity and separation quality in a simple and clear way. The aualitative range of a capillary column, open tubular or micro-packed, is at best expressed by the retention index range at the column temperature and is strongly dependent on the time of analysis. The acceptable temperature range of a capillary column, from far subambient to the acceptable upper limit can be simply expressed by computed data as well as the defined qualitative range. For the precalculation of both simple pocket computer programs are presented.
The ‘four inlet-outlet-concept’ of gas chromatography columns (including capillaries) is discussed briefly; it offers new possibilities for analytical as well as quality check purposes, including accurate measurements of split ratios and flow rates; the tightness of the system under real life conditions can be measured by integrator, by on-line data acquisition systems as well as by hand. Sample transfer lines can simply be made as inactive as the most inactive glass capillary. This is important if we want to use the capillaries in our environment as instrument for quantitative analysis from 100 to 10−10% concentration by split or splitless injection and by capillary enrichment. Quantitative backflush and quantitative hinflush  or other new possibilities for capillaries, run in the four-inlet-outlet-mode, are discussed.
KeywordsCapillary Column Retention Index Splitless Injection Separation Power Packed Type
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