Gowda A T, Gowda N M, Gowda H S, Rangappa K S
J Pharmacol Methods. 1985 Jun;13(3):275-80. doi: 10.1016/0160-5402(85)90028-2.
A simple, accurate, and rapid method for the quantitative determination of penicillin is proposed. The method is based on the formation of a blue penicillin-Azure-C ion-pair that can be extracted into chloroform in phosphate-citric acid buffer. The molar absorptivities for sodium penicillin G and potassium penicillin V at 635 nm were 5.46 X 10(3) and 2.19 X 10(4) l/mol/cm, respectively. Beer's law was valid over the concentration range of 4-80 micrograms/ml for sodium penicillin G and 3-55 micrograms/ml for potassium penicillin v. Maximum absorbance was obtained almost instantaneously and was stable for several days. The method was successfully applied to pharmaceutical preparations.
