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Assay of bensyl alcohol in oil
Posted: Fri Jun 04, 2021 7:03 am
by Mattias
I was asked to run an assay of bensyl alcohol in sesame oil and have googled without success.
I assume that the analytical problem is more related to the sample preparation than the actual HPLC run.
Bensyl alcohol has a fairly low solubility in water, so a liquid/liquid extraction with water will most likely not work? Any trick how to get bensyl alcohol out of the oil is appreciated.
Or could this analysis be done by simple UV-Vis spectrophotometry? Or NIR?
I have found some references to GC analysis, but I do not have access to GC.
Re: Assay of bensyl alcohol in oil
Posted: Fri Jun 04, 2021 12:57 pm
by Consumer Products Guy
Yes, GC better if available.
I would extract the sesame oil with methanol or ethanol (benzyl alcohol will dissolve, most of the sesame oil would not). Maybe even warm it for dissolution then cool it and extract some of the alcohol layer.
There should be no need to saponify the sesame oil (say in KOH-methanol), then neutralizing before injecting.
Re: Assay of bensyl alcohol in oil
Posted: Fri Jun 04, 2021 1:13 pm
by Mattias
Thanks for your suggestion!
I will give it shot on Monday!
Re: Assay of bensyl alcohol in oil
Posted: Tue Jun 08, 2021 8:50 am
by Mattias
I have no tried liquid-liquid extraction of the oil with MeOH, 50% MeOH in water and just water.
Regardless of MeOH concentration, the alcohol layer becomes cloudy and does not clear up if I wait. I have used 1 g of oil in 50 ml of solvent.
Maybe something in the sesame oil precipitates in the alcohol? The benzyl alcohol should be freely soluble in MeOH.
Glad for any tips and tricks!
Re: Assay of bensyl alcohol in oil
Posted: Tue Jun 08, 2021 2:00 pm
by Consumer Products Guy
Regardless of MeOH concentration, the alcohol layer becomes cloudy and does not clear up if I wait. I have used 1 g of oil in 50 ml of solvent.
Maybe something in the sesame oil precipitates in the alcohol? The benzyl alcohol should be freely soluble in MeOH.
Glad for any tips and tricks!
Yes, some of the sesame oil will be in the methanol layer; why is that an issue with your assay? Your benzyl alcohol is now in a solvent amenable with revere phase.
Re: Assay of bensyl alcohol in oil
Posted: Wed Jun 09, 2021 5:35 am
by Mattias
You mean after filtration? I do not want to inject a cloudy solution on my column..
Re: Assay of bensyl alcohol in oil
Posted: Mon Jul 19, 2021 6:48 am
by Mattias
The problem was solved by dissolving the sample in 2-propanol to a clear solution.
And then inject directly on a C18 column with a gradient from 20-100% 2-propanol.
The oil probably precipitates on the column, but it seems to work anyway with a wash step of 100% 2-propanol for 5 minutes. I have done about 100 injections now, and the column still is fine
