The anomalous results reported recently by Steinmanl6 using the manometric assay for studying the rate of 6-APA hydrolysis by penicillinase can be explained by reaction of some of the carbon dioxide with 6-APA to form &HPA. It seems likely that nearly everyone working with 6-aminopenicillanic acid will, at some time, by chance or by design prepare 8- hydroxypenillic acid.
