Studies with marked antisera. Quantitative studies with antisera marked with iodine 131isotope and their corresponding red-cell antigens

Abstract

3. It is suggested that the effect is due to three factors. (a) If magnesia mixture is added to the reduced phosphomolybdate complex and the resulting precipitate analysed colorimetrically, recoveries of inorganic phosphate are low. (b) Free molybdic acid is reduced, giving molybdenum blue. Contrary to prevailing opinions, molybdenum blue is extracted from acid solutions by i8obutanol. ( c) The specific extinction coefficient is about 4-5 times higher when the colour of the reduced phosphomolybdate complex is developed at 1000 than when it is developed at room temperature. This is true for most reducing agents except stannous chloride, with which a higher extinction is obtained at room temperature.