The colorimetric micro-determination of non-esterified fatty acids in plasma

Colorimetric determination of free fatty acids in biological fluids.

Colorimetric ultramicro method for the determination of free fatty acids

In 1964, a method was described for the determination of free fatty acids (FFAs) in vegetable oil. This paper describes an expansion of that work, improving the sensitivity and reproducibility of the method, as well as examination of solubilities of the copper soaps as a function of chain length and unsaturation. Involvement of the micellar structure was reviewed. Finally, a procedure is described that permits very rapid determination of FFA at the 2.0–14.0 µmol (0.5–4.0 mg oleic acid) level, and the results with several oils are given. Particular attention was given to evaluation of solvent systems which would extract the copper complexes.

Rapid colorimetric determination of free fatty acids

Adenosine 3',5'-monophosphate in biological materials. II. The measurement of adenosine 3',5'-monophosphate in tissues and the role of the cyclic nucleotide in the lipolytic response of fat to epinephrine.

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The colorimetric micro-determination of long-chain fatty acids.

1. The use of labelled acetate for studying the synthesis of long-chain fatty acids in rat adipose tissue in vitro has been examined, with special reference to the effect of acetate concentration. 2. The incorporation of acetate into fatty acids is proportional to the concentration of acetate in the medium when the latter does not exceed about 10μm. Above this concentration, the relative incorporation becomes progressively less, and reasons for this are discussed. 3. In particular it is shown that this is not necessarily due to disturbance of the endogenous rate of fatty acid synthesis by a relatively large amount of acetyl-CoA derived from added acetate. 4. However, to ensure that the added acetate does not cause such a disturbance its concentration must be kept sufficiently low. For labelled acetate used under present conditions, this concentration should not be more than about 10μm.

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W. G. Duncombe

Papers

The colorimetric micro-determination of long-chain fatty acids.

Fatty acids synthesis in rat adipose tissue. Tracer concentration effects in vitro