Estimation of 4-Butoxyphenylacetohydroxamic Acid Utilizing the Lossen Rearrangement

A sensitive and specific GLC method for the determination of 4-butoxyphenylacetohydroxamic acid (bufexamac) is described. The trimethylsilyl derivative of bufexamac is chromatographed with docosane as the internal standard. This derivative of bufexamac undergoes the Lossen rearrangement on the column to give a quantitative yield of 4-butoxybenzylisocyanate. Possible metabolites of the drug, 4-butoxyphenylacetic acid and 4-butoxyphenylacetamide, can be simultaneously estimated.