What is a fatty acid?
A fatty acid is a carboxylic acid with a long hydrocarbon change. The carbon chain usually contains between 14 and 24 carbon atoms. There are three types of fatty acids grouped in relation to dietary requirements:
- Essential. These cannot be made by the organism or are made in such low amounts a dietary source is required.
- Conditionally indispensible. These are essential and widely available in the diet, or can be produced by synthesis from other fatty acids.
- Nonessential. Consistently available through diet or easily synthesized from other fatty acids.
How can we use fatty acids?
Fatty acids which are essential can be used as ecological tracers and physiological indicators. Fatty acid signatures have been shown to differ between species and can show seasonal changes within a species. In our lab, we mainly look at the fatty acid signatures to trace food sources in aquatic food webs. The following questions could be answered using fatty acids:
- What does this shark feed on?
- How healthy is this fish?
- How much does each food source contribute to the diet of this animal?
- How do we measure fatty acids?
Fatty acids must first be extracted from tissue samples and dissolved in solvent before being analyzed. We can then measure fatty acids using a Gas Chromatography Flame Ionization Detector (GC/FID). The gas chromatograph is able to separate fatty acids based on their solubility. The sample is injected into the gas chromatograph where it is volatilized and transported to a separation column. The sample than is burned in a FID, which directs the gas output from burning the sample into a hydrogen flame. The compounds produce ions as they burn in the hydrogen flame, and therefore change the electric current within the flame. Changes in the current can then be measured.
Check out the Fatty Acid Services offered at GLIER.