Does a thicker film GC column increase sample loading capacity for PAHs? 30m x 0.25mm x 0.50µm Rxi-5ms

After my post, “Sample loading capacity for PAHs on a 30m x 0.25mm x 0.25µm Rxi-5ms GC column”, a ChromaBLOGraphy reader posed the question about how a 0.50µm column would work.  It’s a great question, because column vendors routinely advertise that thicker films have more sample loading capacity.  But do they really, and if so, how much more?  Let’s test it!

First I used the EZGC Method Translator to get the GC oven program for the 30m x 0.25mm x 0.50µm Rxi-5ms.  Ultimately, the translation results in a slower oven program rate to try and keep the elution temperatures about the same for the compounds of interest so that no compounds suddenly coelute, or worse, switch elution order.  As you can see from the chromatograms below, the 0.25mm x 0.50µm Rxi-5ms does not show a substantial sample loading capacity increase versus the 0.25mm x 0.25µm for the PAHs of interest.  Given that the run times are longer for the thicker film column, and the peak widths are broader (leading to reduced sensitivity), there seems to be no dramatic advantage to using the thicker film column in this case.

25_50 PAH Xlate























25_50_PAH 50


25_50_PAH 25


25_50_PAH 12_5


25_50_PAH 6_25


25_50_PAH 3_13

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