Accelerated amino acid analysis. Studies on the use of lithium citrate buffers and the effect of n-propanol, in the analysis of physiological fluids and protein hydrolyzates.

Abstract A study has been made of the effects of some variables on the analysis of amino acids using Aminex A5 resin and lithium or sodium citrate buffers. Variation of the Li + concentration, pH, temperature, and n -propanol concentration of the buffers showed that the last three variables have an effect on the pattern of the amino acid chromatogram. In the case of n -propanol concentration, this effect is quite marked. An accelerated routine method of analysis of either physiological fluids or protein hydrolyzates is presented. Aminex A5 resin is used in four columns, two of which are the same length. One set of four buffers is used. Total analysis time is 12 hr for a physiological fluid and 4 hr for an hydrolyzate. In physiological fluid analysis both asparagine and glutamine can be estimated while all the other amino acids of major interest are well resolved, as are many less common ninhydrin-positive compounds. Unusual components which are not resolved completely in the routine system in certain cases can be resolved by changes in pH or propanol concentration of the buffers. Pressures at the column top do not exceed 300 psi.