bad peak shape of ehtylene glycol.

[vishall79]

Hi,
I am tryting to analyse Glycoles (dissolved in Methanol) on HP-5 column. I am getting a bad peak shape. I can't use different type of column as the sample contains non polar compounds.
Please suggest any way to improving.

[Consumer Products Guy]

I can't use different type of column as the sample contains non polar compounds.

I don't understand why this is an issue.

If you must stay with an HP-5 column: of course ethylene glycol peak shape will be bad, as it's very polar and your column is essentially non-polar. So if you are wedded to HP-5, dissolve your samples in DMF and make trimethylilyl derivatives of the polar compounds using BSTFA. The derivatized ethylene glycol will elute just after the derivatizing agents, so be sure to run a blank. See Journal of Cosmetic Science, May/June 2010, pp. 1-10.

[Peter Apps]

All else being equal, and as a sweeping generalisation it is usually easier to analyse non-polar compounds on a polar column than polar compounds on a non-polar column, so you may not be as constrained in column choice as you think you are.

What is wrong with the peak shape - front-tailing, tailing, symmetrical broadening ?, splitting. Please post a chromatogram (instructions in a sticky at the top of the page).

A clean, deactivated inlet liner and a new column (even with the same phase) will probably help.

Peter