Haemoglobin - Coated Charcoal for Estimation of Gastric Intrinsic Factor

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Abstract
Vatn, M. H. Haemoglobin-coated charcoal for estimation of gastric intrinsic factor. Scand. J. Gastroent. 1973, 8, 755-760. An examination of the different steps of the charcoal method is described, using haemoglobin as coating material. A within assay precision of 3.7 per cent, and a between assay precision of 4.5 per cent was achieved. An approximately linear relationship was found for the vitamin B12-binding capacity and different amounts of gastric juice in the range of 20-80 per cent of the B12 standard. The results of methodological investigations suggest that neutralized gastric juice should be incubated with antiserum for at least 2 minutes, and vitamin B12 for 1 hour, at room temperature. The present report also indicates that the coated charcoal method is pH dependent, and unreliable for examination of IF-B12 binding at extreme pH values. Comparison between haemoglobin- serum-, and dextran-coated charcoal showed that estimation of IF activity provided similar results with the three coating materials, and that the estimated unspecific B12 binding activity was higher with dextran than with haemoglobin and serum.