Vitamin analysis of protein bar

[chemistrynerd]

I need to analyze a protein bar for vitamin content. The bar has lipid content and I don't want to gum up my HPLC column. How should I extract the vitamins? SPE columns? Which one? Liquid-liquid extraction with a separatory funnel?

[FragranceChem]

If your extraction is not limited to any particular solvent then I would suggest starting with something like a 70/30 mix of methanol/water. What particular vitamins are you looking for? I'm not familiar with what the solubilities of some of the fat soluble vitamins such as vitamin E are in aqueous methanol so it might be a good idea to perform multiple extractions on the same sample to see how much is left over or monitor your recovery.

[Alexandre]

It depends on what you want to do.
If you need data for compliance you need to follow official methods.
Please note that nutritional values of many vitamins are different from LC results and are obtained by microbiological testing.

If you want to develop a new method then attack each vita-min/-mer individually. If you want to use your method later on in your lab you have to demonstrate equivalency of your and official method, or to mention limitations of your method in the report. You don’t want to overdose babies by reporting underestimate of vitamins. LC results are usually lower than bio available vitamins.