Affinity Chromatography: A Precise Method for Glycosylated Albumin Estimation

A method is described for the estimation, in plasma, of glycosylated albumin, using the commercially available affinity chromatographic material Glycogel B (immobilised m-aminophenylboronic acid on an agarose support) to separate the glycosylated and non-glycosylated albumin, followed by the analysis of albumin concentration using rocket immunoelectrophoresis. Glycosylated albumin and glycosylated haemoglobin showed good correlation (r = 0.91) when both are estimated by affinity chromatography. The glycosylated albumin method displays good within-batch (2.8-4.4% CV) and between-batch (2.9-5.4% CV) precision, and the method is not affected by haemolysis. Using this method a reference range of 2.0-5.4% was found for glycosylated albumin. Levels of glycosylated albumin in diabetics (10.06 +/- 3.23%) were found to be significantly higher (P less than 0.001) than those in non-diabetics (3.72 +/- 0.85%). It was found that loading more than 3 mg of albumin on to a 1 mL affinity column must be avoided, as this appears to overload the column.