Manual determination of intra-erythrocytic 2,3-diphosphoglycerate in whole blood by enzymatic analysis, and comparison with ion-exchange chromatography.

A manual modification of an automated method [Atkinson, K. F., Clin. Chem. 18, 1001 (1972)] for enzymatic assay of 2,3-diphosphoglycerate is described, which is suitable for small laboratories. Samples are easily prepared for analysis, and preparations are stable for several months. Virtually all of the color generated in the colorimetric assay is produced by the diphosphoglycerate-catalyzed reaction. The coefficient of variation for multiple samples from a single subject was 2.4%. Delayed preparation of samples, particularly samples from some acidotic subjects, is shown to result in altered results. The enzyme method is compared with analysis by ion-exchange chromatography.