multiple peaks for one analyte

[DylanAnderson]

Hello! I'm working on a comprehensive HPLC-UV method for the analysis of 10 different B vitamins within fortified food products. The riboflavin is giving me some grief. I'll lay out my instrument conditions..I'm running a Waters Alliance e2695 with a PDA detector. I have a few different columns but I've chosen an Xbridge 3.5um 4.6mm by 150mm. The problem is I'm analyzing for riboflavin-5-phosphate and I believe the functional group is causing different retention times on the stationary phase 5 or 6 small peaks with one large one. I've tried a few different mobile phase pH's (3, 5, 7) but no luck. I saw one paper that used an enzyme to cleave the phosphate group but I don't want to get into that...Anyone have any suggestions ?

[vmu]

I believe...

...that your riboflavin-5-phosphate is a mixture of several compounds as this:
https://static.usp.org/pdf/EN/reference ... I1K199.pdf

[DylanAnderson]

I believe...

...that your riboflavin-5-phosphate is a mixture of several compounds as this:
https://static.usp.org/pdf/EN/reference ... I1K199.pdf

Huge help! thank you