Chromatography Forum

We are trying to quantifier fermentable sugars in beer samples but direct injection doesn’t work with NH2 column and RI detector because there isn’t enough concentration . I don’t know if there are some SPE which we could use for this purpose

Unless your RI is very insensitive or the sugar contents very low, I'd expect it to detect the sugars. Check the performance specification and confirm that you have the sensitivity. All you may need to do is filter/centrifuge the sample and inject larger volumes ( eg 100ul ).

Getting rid of water is a pain, especially as other non-volatile components will concentrate. There may be other techniques, such as dialysis, that you can use. But sample concentration with fermentation media can create dark goo very quickly.

I'd also look at the application literature and brewing industry publications, just to see how others approach the problem. Google can be helpful.

Bruce Hamilton

Also, try to change the gain (or multiplication factor) to 'magnify' the peak. You can do this within most CDS's.
Alfred