Does anyone have a method or a suggestion for a method to quantify sodium acetate in a solution containing 1% sorbitol & 45g/l protein.

not a chromatography problem, try an ion selective electrode.

Analysis of sodium acetate can be done by ion chromatography. There are a two options: cation analysis for sodium or anion analysis for acetate. If you choose to look at sodium, watch out for the glassware. You may need to remove the proteins, but that should be able to be done with SPE. Now, whether you should go through the trouble of developing the IC method rather than using an electrode is up to you, your workload and how routine you expect this analysis to get. In our lab, use of IC over titrations or electrodes depends on the number of samples. A small number would dictate the use of an electrode or titrations. Because we have an autosampler, larger numbers of samples are often analyzed by IC.

If you want an LC method see my response for the sulfonic acid question. Same conditions and same columns do acetic acid nicely. 205 nm With the best detector you can do less than 1 ppm. If you want a reference.....J. Chromatogr. 868 (2000)41-50. Figure 1.

Should be easy for acetate. Clean up the proteins from your sample using SPE as suggested by B. Kochanowski, acidify the sample and do a direct injection onto a Rezex ROA Organic Acid Column, or any equivalent sulfonated styrene - divinylbenzene column. Mobil phase water 0.005N H2SO4, 0.6 mL/min, detection UV 210 nm. If you have a column oven try somewhere between 40 - 60 C.

Much easier than IC. Can use any isocratic LC system.

Use SPE if you have to. Depending on your sensitivity needs you may be able to precipitate the protein with a 1:1 dilution with ACN then filter. Make sure that you are not precipitating acetate.