G'day People,
My name is Greg and i have for sometime now been analysing environemntal samples for organic acids, mainly in water and soil samples. Currently we use a PO4 buffer with methanol gradient on a C18 (5um, 250mm*4.6mm) RP column. Currently, we are able to analyse for: formic, malic, malonic, lactic, acetic, maleic, citric, succinic, fumaric, cis-aconitic and trans-aconitic acid.
However, i would very much like to analyse for oxalic aicd, which unfortunately elutes very close to the void in both RP and IC .
Does anyone have any experience with organic acid analysis especially oxalate and would be keen to strike up an email relationship to discuss methodologies, etc...

Regards from downunder

Greg

Hi Greg,
please have a look on J. Chromatogr. A Vol.: 850 p: 187 - 196 (1999) Separation of carboxylic acids on a weakly acidic cation-exchange resin by ion-exclusion chromatography, Kazuhiko Tanaka, Hisao Chikara, Wenzhi Hu, Kiyoshi Hasebe. Perhaps we can discuss one of your chromatograms by e-mail. My address is: g.kratz@tosohbiosep.de! Regards from Bavaria
Gerhard

Fair results were obtained in the analysis of oxalic in urine with a Hypercarb column from Shandon (now Hypersil?). An example of the manufacturer was slightly modified.
Incidentally, this was the only useful application of TFA in chromatography ever seen here.

Greg,

Is there some reason you are not considering anion exchange for this application? The analytes you listed can be separated by anion exchange using a hydroxide gradient on an AS11 column.

Hi all again,
Many thanks to the those who have replied, greatkly appreciated indeed.

Gerhard,
Thanks for the reference, will look into it for sure. And yes, i would be delighted to be able to discuss with you the separations we are dealing with at the moment

Chris,
Yes i have looked into the Dionex system, although not too intensely. We have 3 good Waters systems here and when i last spoke with Dionex some 12months ago, they would not deal with us as we did not have a dionex system, thus could not purchase a dionex column!! Not sure if that is the deal where you are. In addition, i spoke with a HPLC scientist at the Chemistry Centre here in Perth (Western Australia)and their comments on the dionex separation with NaOH eluent were not that promising, hence why we didn't follow up. Our current RP method is a good one i believe, with good agreement between standard addition, enzymatic assays and straight LC calibration regressions.

Regards
Greg

Shodex shows an application for oxalic acid on their Ionpak KC 811 (expensive!): RI-Detektion (sensitivity?), 50 mMol HClO4.Retention Time about 12 min with 2 columns.But I didn't test it.
Peter

We analyze for oxalate using a dionex AS-9 and a isocratic CO3/HCO3 eluant.

I've used the KC811 for analysis of organic acids and alcohols pretty successfully and with reasonable sensitivity (ppm level MQL if I recall correctly) on a Waters system equipped with a 410 refractometer and a pulse dampener. Sample prep took some fiddling, as my sample had 2 mg/mL protein, which the column did not like, but I was able to play some SPE games and get a decent assay. One major criticism is the run time - quite long, however high temperature can be used to shorten somewhat.

Thanks to everyone who have provided some information, greatly appreciated indeed!!
I shall follow up and if i remember, one day post the outcome here.

thanks again.

Regards
Greg

Good Day:

I was wondering if anyone knew if there is a GC column that will be able to give good quality analysis of Fumaric and malic acid along with acetic, propionic, butiric, valeric, etc. acids?

I know there are HPLC columns that do that but, I was wondering if GC can be used as well..

Thank you for your help...