Measurements of plasma free fatty acids (FFA) concentration and isotopic enrichment are commonly used to evaluate FFA metabolism. Gas chromatography-combustion-isotope ratio mass spectrometry (GC/C/IRMS) are considered to be the best method to measure isotopic enrichment in the methyl derivatives of 13C-labeled fatty acids. Although IRMS is excellent for analyzing enrichment, it requires time-consuming derivatization steps and is not optimal for measuring FFA concentrations. A new methods is developed it is rapid, and reliable method for simultaneous quantification of 13C-labeled fatty acids in plasma using high-performance liquid chromatography-mass spectrometry (HPLC/MS).

Hi,

I don't think you can measure FFAs by spectrophotometry only. You'll need to use gas chromatography (GC) with FID or MS detectors. This method implies to form the methyl esters (FAMEs) by reaction with KOH in methanol and further extraction.

Hope this may serve  

I would recommend this web resource: http://lipidlibrary.aocs.org/

You will find great deal about FA analysis, derivatization, etc. Usually GC-MS is the method of choice for FA analysis.

Generally speaking the protocol you are looking for will consist of several steps namely: 

Extraction, clean up, partitioning (to separate other lipids), concentration of fractions, derivatization (if GC is used), analysis.

Good luck!

Plasma free fatty acid by spectrophotometry can be assayed with use of enzymatic kit from WAKO.

http://www.wakodiagnostics.com/r_nefa.html

Malgorzata Jaworska ,

Did you have a "micro technique protocol" using Wako NEFA Kits? Because they are designed for automated analyzers. I know that one can adapt to ELISA plates.

Thanks