Single-column chromatographic analysis of labeled glutamine and other amino acids in whole blood

A method is presented for single-column analysis of the concentrations and specific activities of the free amino acids in both whole blood and plasma. Interference from glutathione in whole blood was eliminated by the use of sodium sulfite although losses of about one-half of the cystine and methionine occurred. Seventy-five percent +/- 1 of the glutamine was recovered consistently in both whole blood and plasma so that corrections for this loss readily could be made. Elimination of the baseline shift due to ammonia was accomplished by passing the buffers through ion-exchange columns before entering the sample loops. There were several significant differences between amino acid concentrations and specific activities in whole blood and in plasma, indicating that care should be taken in interpreting data on metabolism of amino acids.