Does anyone have a method to control citric acid by HPLC/MS ?

Thanks in advance !!!

And how would you like it controlled?

Citrate is easily separated by ion exchange from other carboxylic acids and inorganic anions using an AS11 or AS11-HC column with a sodium hydroxide eluent and an ASRS-Ultra suppressor.This separation scheme is interfaced to negative electrospray MS and detection is at a m/z of 191. Dr. Ralph Bruckner also presented a poster on the Kreb Cycle acids by IC-MS-MS at HPLC 2001 in Maastrict.

If the sample is not real complex you can save a bundle of bucks by running it on a C-18 using 5% MeOH + 95% 0.2% phosphoric acid at about 1 mLmin with UV detection at 215 - 220 nm. Anohter excellent choice is an ion-exclusion column such as Alltech AO-1000 or Bio-Rad HPX-87H. Mobile phase for either is 0.01N sulfuric acid in water, column temp is 60C detection is UV at 210 nm, flow is about 0.5 mL/min.

Hope this helps some,
Mark

Thanks all for your comments !!

I was thinking on controling the amount of citric acid by MS and using a simple RP method.

The idea is to prepare a calibration curve and quantify the amount of citric acid in a solution in methanol without anything else in the sample solution.