A method of colorimetric estimation of noradrenaline and adrenaline in a mixture and its application to the medulli-adrenal extracts.

Abstract

1) A method for the differential estimation of noradrenaline and ad-renaline by employing the permanganate reagent was described in detail. 2) This method depends on the fact that the two substances are oxidized at pH 3.6 with permanganate in the different oxidation rates. At pH 3.6, adrenaline is completely oxidized within 2 minutes, whereas only less than 10 per cent of noradrenaline can be oxidized during the same oxidation time. At pH 5.6, however, both noradrenaline and ad-renaline are fully oxidized within 3 minutes. 3) For differential assay of noradrenaline and adrenaline in a mix-ture, a sample for assay is oxidized at pH 3.6 for 2 minutes and at pH 5.6 for 3 minutes. By determining the colour densities, the amount of norad-renaline and adrenaline can be calculated from the given formulas. 4) The method has been applied successfully to the medulli-adrenal extracts of cattle and horses. In practising, the colour tint of the extracts and the standard adrenaline solution after oxidation was almost similar. The noradrenaline content estimated per g. of adrenal medullary tissue was 2.89mg. (1.02-4.57mg.) in cattle and 1.95mg. (1.47-2.63mg.) in horses. The adrenaline content was estimated to be 7.03mg. (4.57-9.47mg.) in the former and 8.70mg. (7.35-10.47mg.) in the latter. Therefore, noradrenaline was found in the medullary tissue in an amount of 29% (14-39%) of the total in cattle and of 18.5% (12-26%) in horse. I wish to thank Prof. T. Suzuki, at whose suggestion this work was carried out, for much valuable advice and encouragement. I am greatly indebted to Drs. T. Kawachi and Y. Baba in Mitsui Institute of Industrial Medicine for practising the spectrophotometric determinations.