Spectrophotometric method for the specific determination of phenoxymethylpenicillin

Abstract

A spectrophotometric procedure for the specific determination of phenoxymethylpenicillin is described. Benzylpenicillin, n-heptylpenicillin and other acid-unstable penicillins, if present, are decomposed by treatment with acid prior to assaying for total penicillins. The acid-stable penicillin content is then corrected to phenoxymethylpenicillin by subtracting the p-hydroxyphenoxymethylpenicillin content, normally the only acid-stable penicillin impurity that occurs, and which is determined separately.