Detection of membrane fragments in hemoglobin solutions

Two methods for the detection of membrane components in human stroma-free hemoglobin (SFHb) solutions are described. The first method is a phospholipid assay with a detection limit of 0.5-1 nmol phospholipid/ml SFHb. For the detection of membrane proteins an immunoassay with a monoclonal antibody against glycophorin alpha was developed (detection limit 0.01% of the original amount). The determination of both glycophorin alpha and phospholipid yields useful information on the purity of SFHb solutions, as was shown by determination of the purity of two SFHb solutions prepared in different ways.