The "HemoQuant" test: a specific and quantitative determination of heme (hemoglobin) in feces and other materials.
We describe a new, specific, quantitative method for fecal blood, based on conversion of nonfluorescing heme to fluorescing porphyrins, that obviates serious deficiencies inherent in currently used tests. A two-reagent system is used to determine the two hemoglobin-related fractions that are found in feces. The hot citric acid extract includes only the variable fraction of porphyrins that have been preformed from heme in the intestinal tract; this often is the major fraction. Total hemoglobin is indirectly determined by reaction with heated oxalic acid:FeSO4 reagent, which converts the remaining heme to porphyrin without loss of the preformed porphyrins. A three-step purification procedure eliminates interfering materials. Analytical recovery of added hemoglobin is linearly related to concentration over a several-thousand-fold range. The assay is equally applicable to whole blood or to sub-microgram amounts of hemoglobin in the 8-mg (wet weight) fecal sample tested. Quality control by liquid chromatographic and fluorometric analysis documents fluorescence specificity of the heme-derived porphyrins.
D002851:Chromatography, High Pressure Liquid; D004064:Digestive System / Q000378:metabolism; D006418:Heme / Q000032:analysis* / Q000378:metabolism; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D009780:Occult Blood; D010070:Oxalates; D019815:Oxalic Acid; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000032:analysis / Q000302:isolation & purification; D013050:Spectrometry, Fluorescence; D013223:Statistics as Topic
D006454:Hemoglobins; D010070:Oxalates; D011166:Porphyrins; D006418:Heme; D019815:Oxalic Acid