TPGS

[shuimu]

TPGS is one of excipient in the product and it give lots of peaks through out the whole run due to the different molecular weight distribution. The current method is barely ok for the low concentration of TPGS. What I can do if the TPGS is 5 times higher. By the way, UV dectector was used in previous method and TPGS has absorbance among all API sample UV spectrum.

[AdrianF]

You will need to extract your molecule of interest from the mixture. I would give SPE ( solid phase extraction) a try.

[shuimu]

Thanks. Anything else?

[Mattias]

I assume that TPGS is a polymer, and in that case you could try to separate the molecules by size before the reversed-phase separation.

1. Size-exclusion in combination with a reversed-phase trap column (column switching).

2. RAM (restricted access media) column

Otherwise you could have to look at other detection techniques (fluorescence?)

[JGK]

If you mean D-alpha-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS).

It's water soluble, you could try modifying the chromatography to elute it from the column faster than the API.