Abstract
The potency determination of Fradiomycin had relied on biological method and the present studies were carried out in order to find a simple colorimetric method for its determination. To 5cc. of a sample solution placed in a glass-stoppered test tube, 5cc. of 2% isoamyl alcohol solution of lauric acid and 0.5cc. of 5% sodium carbonate solution were added, the mixture was shaken vigorously, and centrifuged. Four cc. of the isoamyl alcohol in the upper layer was transferred to a new glass-stoppered test tube, 5cc, of distilled water and 0.2cc. of 50% acetic acid solution were added, and the mixture was shaken for 5 minutes. Four cc. of the lower aqueous layer was transferred to a new test tube, 1cc. of 20% sodium carbonate solution was added, and shaken thoroughly. The mixture was cooled in ice water, 0.5cc. of 1% sodium 1, 2-naphthoquinone-4-sulfonate solution was added, and allowed to stand in ice water of 0° to 2° for 20 minutes. To this mixture, 2cc. of an equivolume mixture of acetone and ethanol was added, followed by 0.5cc. of 50% acetic acid solution. At the same time, blank test was carried out with distilled water in place of the sample solution and treated in the same way with the same reagents. Using this as the control, absorbancy was measured at 460 mμ and the potency of the sample solution was calculated from the calibration curve of Fradiomycin.
Determinations were carried out by this method on the samples sterilized by boiling and treated with acid and alkali, and a sample solution allowed to stand for a long period. The values so obtained were compared with the values obtained by the cup method, given in the standard for antibiotic preparations and the two values showed good agreement.
