Chromatography Forum

hi all,
i need to determine low ppm levels of some small acid (very low pka) in commercial sugar. Sorry, I can't give more info.
at that ppm level i need to use ELS or MS/MS for detection, which i don't have. So, the alternative is derivatization but the sugar is interfering.
do you know how can I remove the matrix (sugar) from the solution?

i appreciate your advice
thanks
sergio

Solid-phase extraction with a mixed-mode anion exchanger might be the best solution.
Dissolve the material in water. Load it onto an Oasis MAX anion exchanger. The sugars will break through. Wash clean of sugars with some additional water. Then extract the anion with a suitably acidic acid (dilute HCl, H2SO4, H3PO4...).

A weak ion exchanger might do as well (Oasis WAX).
Acidify the ion-exchanger. Load your sample in water (sugars will brek through). You are left with the bound acid, which can be released with ammonia as the ammonium salt.

thanks Uwe,
i'll try oasis max, it seems to be more suitable for my application

thanks again
sergio