Cross-linked agarose activated with carbonyl diimidazole and subsequently coupled to aminophenyl boronic acid provides a highly efficient matrix for separation and quantitation of glycosylated hemoglobins The method described is highly reproducible. rapid and flexible in that it can be adapted to column or batch formats The method can tolerate moderate fluctuations in temperature and pH of buffeused without significantly altering results Hemoglobin fractions separated by this affinity support were Subjected to isoelectric focusing which revealed a heterogeneous population of glucose modified proteins.