Simple micromethod for the isolation and determination of amino acids in biological fluids using ion exchange resins and paper chromatography

Abstract

A fast micromethod for isolating amino-acids in biologic fluids lias bcen started, as a previous treatment to its paper chromatography study.

In a small column with 2 mi. capacity, 0.4 gr. of resin lon-X (Dower 50 x 12) are placed, reaching a height of 22 mni. over a cotton-wool plug.

After the previous alternating treatment with an acid and an alkali, it is left in acid form and is washed with wateruntil the fluids comes out neutral. Then 200 pl of biologic fluid are added, they are passed at a rate of 20 drops/minuteand are washed with 10 mi. of water. They are eluted with 4 mi. of ammonia 2 N and are divided into two parts. The first is evaporated and diluted in order to do a bidimensional chromatogram. The second is evaporated, hydrolized with HC1 5-6 N during 5 hours, treated again with resin, oxidized with H2O2 and concentrated for another chromatogram.

Comparing both results the sulfur-contaiuing amino-acids, the amides and the peptides are identified and an idea of their composition is obtained. With the help of an adequate map and standard chromatogram at different dilutions, all of the amino- acids in the problem fluid are identified and their concentra- tions valued.