Promlems with AD3E vitamins

[xeim]

Hello guys,

Im trying to carry out the analysis of a product that contains vitamins A, D3 and E diluted in oil. Previously, the Hyper Clone 3u BDS C18 130A (100X4,60mm) was used to analyze and separate substances. However, it was found that peak from oil matrix jumps with D3 peak together. By the reason this column was changed by Kromasil 3,5u C18 (150x4,60mm). At the beginning the Kromasil column worked normally but later a problem with excessive pressure appeared. The column couldnt tolerate eluent flow rate 1,5 ml/min.
Could you tell me please if Hyper Clone 3u BDS C18 130A with bigger length will help to separate the oil matrix peak from D3 peak. Or what could be a solution of this problem?
Thank you in advance,

[Gerhard Kratz]

C18 is never the same and one C18 column cannot solve all problems.
What kind of sample preparation did you?
Did you centrifuge your sample? 1,5ml/min is not a problem for the Kromasil column, but if oil is on the packing material pressure will go up.
Did you look up specific application notes from various manufacturers? Latest application note I got on my desk was from Nacalai Tesque with a special Cosmosil column for fat soluble vitamins.

[danko]

xeim, do you filter your sample solutions?