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- Posts: 16
- Joined: Tue Feb 15, 2005 2:16 pm
Since soy bean lipids contain 5 different fatty acid chains you get a lot of peaks in a RP-method. In my experience a NH2-column with a mobile phase containing ACN/MEOH/NH4acetate buffer works well, when you just want to get one peak for each lipid type (-serine, -ethanolamine, -choline...).
I don't have any experiences with your derivatisation method. I was just working with RID, ELSD and UV.
I agree with you all, that ELSD would be the best choice, but since we are taking about Phosphatidylserine in tablets (surely no trace amounts), I would suspect the RID to be sensitive enough. With UV you get reasonable signals at 200-215nm (from the unsaturated fatty acid) but the response factor strongly depends on the fatty acid chain. So it is not suitable for quantification, but a nice tool to get an idea about the degree of oxidation: During the oxidation the isolated double bounds (Linoleic and linolenic acid) change to conjugated double bounds, thus creating new absorbance maxima at approx. 230nm and 280nm.
It is reported in literature, that RID gives the same response for all lipids. Well, its a approximation, one can work with
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I saw (when working with Phosphatidylcholine) slight differences for different chain lengths and degrees of unsaturation.
I don't have any experiences with your derivatisation method. I was just working with RID, ELSD and UV.
I agree with you all, that ELSD would be the best choice, but since we are taking about Phosphatidylserine in tablets (surely no trace amounts), I would suspect the RID to be sensitive enough. With UV you get reasonable signals at 200-215nm (from the unsaturated fatty acid) but the response factor strongly depends on the fatty acid chain. So it is not suitable for quantification, but a nice tool to get an idea about the degree of oxidation: During the oxidation the isolated double bounds (Linoleic and linolenic acid) change to conjugated double bounds, thus creating new absorbance maxima at approx. 230nm and 280nm.
It is reported in literature, that RID gives the same response for all lipids. Well, its a approximation, one can work with
.I saw (when working with Phosphatidylcholine) slight differences for different chain lengths and degrees of unsaturation.
