1994 Volume 43 Issue 1 Pages 17-23
A rapid method was proposed for the determination of myoglobin by the potentiometric argentimetric titration of iodide ions, liberated in proportion to the amount of myoglobin at constant condition when myoglobin was treated with an iodine-ethanol solution using an iodide-selective electrode. The reaction ratios of standard amino acids to iodine, stability of the myoglobin, effect of the amounts of iodine, effect of ethanol, effect of temperature, effect of added sulfuric acid, effect of the reaction time, effect of concomitant compounds and precision data of myoglobin are discussed. The recommended procedure was as follows. A sample containing 0.14414.4 mg myoglobin was taken into a 50 ml-titration cell and treated with 5 ml of a 5 mM iodine-ethanol solution. In addition, 3 ml of 1 M sulfuric acid was introduced into the sample solution. The volume was adjusted with distilled water to 50 ml which was then titrated potentiometrically with a 330 mM standard silver nitrate solution. These procedures were performed at room temperature (25°C). Upon the addition of sulfuric acid, the potential jump of the titration curve was enhanced. Myoglobin (0.14414.4 mg) was determined with an RSD less than 3.8% at room temperature (25°C). The calibration curve was drawn using the equation Y=0.235X+0.0009, Y being the added silver nitrate weight in mg and X the myoglobin weight in mg. The coefficient of correlation was 0.999.
