Batch to batch imprecision in the affinity chromatography assay of glycated hemoglobin

An affinity chromatographic method (AC) was compared with ion exchange chromatography (IEC) for determination of glycated hemoglobin (gHb). In vitro, increasing glucose concentration produced no change on AC-determined gHb. gHb measurement by AC was highly correlated with mean blood glucose (r = 0.96). Mean values of gHb were apparently higher, and variation greater, by AC than by IEC. Intra-assay variation was 2.0% and 3.0%, respectively. Inter-assay variation was 4.8% by IEC and 6.4% by AC. When different batches of AC-columns were compared, mean values as well as precision differed considerably. The affinity chromatographic method tested here shows several expected advantages, but precision and inter-batch variation of the columns remain to be improved.