The measurement of SCFAs is not trivial as. most methods struggle with the highly variable background levels of some of the SCFAs, particularly acetate and butyrate. There are several publications that have reasonable methods (most of the useful info may be in the supplementary)

GC methods

Zhang S, Wang H, Zhu MJ. A sensitive GC/MS detection method for analyzing

microbial metabolites short chain fatty acids in fecal and serum samples.

Talanta. 2019 May 1;196:249-254. doi: 10.1016/j.talanta.2018.12.049. Epub 2018

Dec 16. PMID: 30683360.

and

Furuhashi T, Sugitate K, Nakai T, Jikumaru Y, Ishihara G. Rapid profiling

method for mammalian feces short chain fatty acids by GC-MS. Anal Biochem. 2018

Feb 15;543:51-54. doi: 10.1016/j.ab.2017.12.001. Epub 2017 Dec 6. PMID:

29221706.

Also we developed a method adapted from previous methods that works well and is fairly robust to the background variation

Brignardello J, et al Characterization of diet-dependent temporal

changes in circulating short-chain fatty acid concentrations: A randomized

crossover dietary trial. Am J Clin Nutr. 2022 Sep 22;116(5):1368–78. doi:

10.1093/ajcn/nqab211.

Also there are various LC-MS methods such as

Valdivia-Garcia et al Journal of Pharmaceutical and Biomedical Analysis 221 (2022) 115060

It depends whether you want to measure a wide range or just the main ones in which case the reference below outlines a method that is robust and relatively simple.

De Baere S, Eeckhaut V, Steppe M, De Maesschalck C, De Backer P, Van

Immerseel F, Croubels S. Development of a HPLC-UV method for the quantitative

determination of four short-chain fatty acids and lactic acid produced by

intestinal bacteria during in vitro fermentation. J Pharm Biomed Anal. 2013

Jun;80:107-15. doi: 10.1016/j.jpba.2013.02.032. Epub 2013 Feb 28. PMID:

23542733.

Hope this helps