Chromatography Forum

I have one tripropylene glycol sample to run for assay. My column is supercolwax-10, 60m,0.32mmID, 0.5um. But seems that dipropylene glycol and tetrapropylene glycol cannot separate from tripropylene glycol. How?

In my lab we'd try first to dissolve in DMF, derivatize with BSTFA, and use a non-polar capillary column. Expect multiple peaks.

On a 30meter Equity 1 0.53mm 1.5µm film splitless with pulsed injection, oven @ 50°C to 200°C @ 8°/min gives 4 peaks for diproylene glycol at about 12 min retention for a 100 ppm solution.

This is without derivitization but with excellent peak shape.

I would prefer C P Guy's method.

I suspect that you may not be eluting the other analytes from the column or that your injector temperature is too low.

Try using a 5 or 10m column, preferably a 1.0µm methyl silicone or a thin film FFAP column (instead of a Wax) if you need an analysis on a polar phase.

But I would follow C P Guy's method on a 0.5µm 0.32 or 0.25 mm ID MS non-polar column with derivitization as a trimethylsilyl ether derivative .

You could also make the di acetate derivative of the diols and run on non-polar or polar as well.

Rod