Chromatography Forum

Hello,

I am new to this forum. I have a question about separation of both mineral oil and oleyl alcohol, excipients in my formulation. Currently i am using GPC columns ( 2 columns connected) and THF as mobile phase and extraction solvents. RI detector for detection. I don't think i can separate oleyl alcohol from oleyl alcohol using this method. Can some body give me advices

thanks

subha

I don't think i can separate oleyl alcohol from oleyl alcohol using this method

That separation is impossible

However, typographical errors aside, GPC is based on molecular weight. Oleyl alcohol has a MW of 268. What is the MW of the mineral oil you are using?

Off the top of my head, I would guess that something like normal-phase chromatography would be a better choice.

Thanks for the reply. Currently I am using two GPC columns connected in series for the assay of Mineral oil. It is a huge broad peak. I am sure Oleyl alcohol will elute at the same retention time on those columns. I am wondering if i can use one reverse phase column before the GPC column. ( I am using GPC columns using RI detector : mobile phase :THF as it extracts the mineral oil from the transdermal patch).

Any advices please

Reversed-phase might work, but why bother with the GPC column? It seems that it only contributes band broadening.

Personally, I would probably assay the oleyl alcohol by GC after extraction with DMF and trimethylsilylation. I don't think the mineral oil will be too soluble in DMF, especially if you chill it.