Evaluation of a simplified microchromatographic technique for hemoglobin A2 determination

The simplified Hb A2 determination based on microchromatography in Pasteur pipets filled with DEAE-cellulose with glycine-KCN-NaCl as developers [14] is compared with a reference Hb A2 determination procedure based on starch-block electrophoresis. The utility of microchromatography as a routine Hb A2 assay and as a screening method to detect beta-thalassemia trait carriers and patients with iron deficiency anemia was investigated. Day-to-day variation of a control hemolysate and the correlation between the values obtained with the two methods and between determinations in duplicate on the same sample are given. The mean values obtained with both methods for the different groups do not differ significantly but the standard deviations and the coefficients of variation observed by the microchromatography are generally higher. Microchromatography in Pasteur pipets tends to overestimate low and normal Hb A2 concentrations and to underestimate high Hb A2 concentrations. The results of microchromatography are more significant for the diagnosis when Hb A2 concentrations are expressed in weight hemoglobin per volume of blood and not in percentages. The microchromatographic procedure was recently marketed. The results obtained with the commercial columns were in good correlation with those obtained with starch-block electrophoresis, but commercial columns give a 18% overestimation of the Hb A2 concentrations.