Free Amino Acids in Biological Material

Aqueous extracts of animal or plant organs, fruit juices, homogenates and body fluids generally contain peptides, proteins, carbohydrates, urea, salts and lipoids in addition to free amino acids in water-soluble or emulsified form. 

Ion exchangers which adsorb amino acids are also suitable for deproteinisation. Proteins are only weakly adsorbed for steric reasons and consequently largely pass 

Electrolytic demineralisation partially converts arginine into ornithine and 10—30% of the histidine, lysine, methionine, proline and tyrosine are lost [30], Losses also ensue occasionally from demineralisation with ion exchangers arginine and possibly lysine are not retained by strongly basic exchangers and are difficult to elute from acid exchangers. 

The following ion exchange procedure, based on a method of DbIizb et al. [32, 33], has proved successful in our laboratory [31] for removing both sails and soluble carbohydrates  

In order to test recovery, analysis of amino acids after treatment with an ion exchanger was carried out on (i) an aliquot of serum (ii) an aliquot of the same serum after known amoimts of amino acids had been added and (iii) an artificial amino acid mixture of known composition, similar to that occurring in serum. 

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P Furst, L Pollack, TA Graser, H Godel, P Stehle. Appraisal of four pre-column derivatization methods for the high-performance liquid chromatographic determination of free amino acids in biological materials. J Chromatogr 499 557-569, 1990. 

Other Techniques for the Separation of Free Amino Acids in Biological Materials. 169... 

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