Short chain fatty acid analysis, GC or HPLC?

[valin]

Hi,

I'm doing short chain fatty acids assay (acetic, propionic and butyric acid) for my final project.
I want to ask, which apparatus is better for the assay, GC or HPLC? I have browsed and i found various journals using GC or HPLC, so i am confused which one i should pick. Any suggestions/comments would be most welcome, as I am very new to this analysis

thank you

[Don_Hilton]

Either technique can determine organic acids. The question is what matrix and concentration range are you working with? The steps in obtaining an extract to analyze may guide the answer.

[valin]

Hmmm... could you explain how the matrix and the concentration range affect the method?
Because my objective is to measure the concentration of SCFA.

[Don_Hilton]

You need to present your sample to the instrument in a form and degree of purity that the instrument can provide a good separation from matrix components and detect the analytes.

Concentration range is important. If you are attempting to measure these compounds in a biological fluid the compounds will need little or no concentration in sample preparation to provide sufficient quantities to the instrument for analysis. If you are looking for short chain fatty acids in drinking water, you may need to have concentration steps. And the selection of concentration steps would involve the sample being in water, as solvent, or adsorbed in a SPME fiber.

The matrix is quite important. If you were looking for moderate concentrations of these compounds in a sample that is mostly water, simple acidification and headspace sampling might work well enough. However if you are attempting the analysis in fatty tissue or peanut butter, the headspace approach would not be particularly appealing.

Part of the reason as to why you find so many methods in the literature is that there are so many unique analytical problems that individual matricies create.

Often the selection of instrument for analysis in labs I have worked in has been a quick look to see which instrument was not in use on some other project. The difficult part has almost always been how to start with a sample that may be "dirty" or highly complex and reduce it to something that can be presented to an instrument to obtain reliable results.