Chromatography Forum

I am looking for suggestions in analyzing C1-C7 aliphatic acids in a water matrix that has can have % level of ethylene glycol present. We are looking for detection limits in the range of 10 - 50 ppm. What type of SPE and or sample prep would be appropriate? Any column and/or mobile phase suggestions are also welcome.

Call Grace/Alltech technical support and ask them. I've been happy with their Prevail Organic Acid column.

Dionex offers the Acclaim Organic Acid column for this application. It is a silica based high-efficiency RP column which is fully compatible with highly aqueous mobile phases. The column housing is non-metallic - PEEK, which would minimizemetal contamination from SST column hardware.

The condition for separating C1 to C7 organic acids:
Column: Acclaim OA, 150x4.0 mm
Mobile Phase: A - MeCN, B - 0.05% phosphoric acid or methanesulfonic acid
Gradient: 0 to 45% A in 11 min and keep for 5 minute (minor modification might be needed)
Flow rate: 1 mL/min
Detection: UV at 210 nm

Here is the typical result you should expect (in Figure 7).
http://www1.dionex.com/en-us/webdocs/25 ... OA_V22.pdf

Due to low wavelength detection, the mobile phase needs to be of carefully prepared with high quality reagents.

If ethylene glycol content is less than 5%, I don't expect too much of trouble. If it does impose some difficulties, using a 250x4.0 mm column should help to some extent.

In case these acids can be analyzed by a RP column due to matrix effect, please let me know so that I can offer an alternative.

Good luck!

We have customers using Unison UK-C18 for organic acids as well.
(using 0.1% H3PO4 as their mobile phase).

Depending on what you are analyzing, you may have analytes eluting with k'<1.
So you should look for dispersion from your LC (e.g. autosampler, tubing, detector).
Also make sure you sampling rate is high enough on your aquisition software.

Thanks for all of the suggestions!!