SPE for Stevia

[MSCHemist]

I am working on artificial sweeteners. Does anyone have a good SPE for steviol glycosides. I am trying to quantitate it in protein drinks and powders and carrez isn't sufficient. I am operating at UV210 and steviol glycosides have a low response with that so I need a really clean extract. Steviol glycosides give about 1/10 the signal of other sweeteners like aspartame, acesulfame.

Literature shows both normal phase silica SPE and C18 might work.

[MSCHemist]

I tried a syringe c18 cartridge Macherey Nagel 731802 primed with methanol then water. I put 1ml sample onto it washed with 5ml water then eluted with 2 times 5ml of 80% acetonitrile. It reduced the blob matrix a fair amount but there was still a fair amount present coeluting.

There is a silica normal phase protocol but the sample needs to be in ethanol and then only 0.1ml can be applied and then eluted with 1ml so a 10x dilution plus the trouble of evaporating the sample first then possibly after the elution again.