title: Evaluation of the precision of difference chromatography.
abstract: Difference chromatography, a method of chromatography in which elution volumes are compared directly, has been tested for precision under conditions used for estimating the relative dissociation of human oxyhaemoglobin and methaemoglobin and their hybrid. The test was carried out by first establishing a steady flow of haemoglobin through a column of gel particles, and then interrupting the flow temporarily by injecting a known weight of buffer solution, which thus simulated a small difference in elution volume. The dip in absorbance on the elution record was evaluated by digital methods. Statistical analysis of the results showed that the injected weight was estimated from the elution record with a standard error of plus or minus 0.02 g. Since the elution weight was about 50 g, the precision of difference chromatography must approach that of difference ultracentrifugation, and has obvious potential for the accurate comparison of the molecular weights of polypeptides in strongly dispersing media.
mesh_terms: D002850:Chromatography, Gel / Q000379:methods*; D004591:Electrophoresis, Polyacrylamide Gel; D005069:Evaluation Studies as Topic; D006454:Hemoglobins / Q000302:isolation & purification*; D006801:Humans; D008433:Mathematics; D008706:Methemoglobin / Q000302:isolation & purification*; D008722:Methods; D008970:Molecular Weight; D010108:Oxyhemoglobins / Q000302:isolation & purification*; D013696:Temperature
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; D008706:Methemoglobin