A new colorimetric determination of 6-aminopenicillanic acid has been developed for use with fermentation media. The method depends on removing most of the interfering substances by dialysis, and forming a colored Schiff Base with p-dimethylaminobenzaldehyde. By adapting the method to the Technicon AutoAnalyzer, the entire process has been automated, requiring only an occasional preliminary centrifugation. Reproducibility is about 2% and calibration variability 1 to 4%, at the 95% confidence level.Relative error is -2 to +1% over the range of 600 to 4000 pg./ml. Operating variables and interferences have been investigated.

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N. Y. 13201 An Improved hydroxylamine determination is described for cephalosporins, offering adequate sensitivity, stable test and blank solutions, and good precision. Cephalosporins react more slowly with hydroxylamine than do penicillins, so that hydroxylamine methods used for penicillins suffer from Incomplete reaction and poor reproducibility when applied to cephalosporins. Work was undertaken to develop a suitable hydroxylamine method for process control of cephalosporins. The effects of reagent concentration and reaction conditions are discussed. Nlckel(ll) was found to catalyze hydroxamic acid formation of cephalosporins and to stabilize the color formed with Iron(lll). Optimized manual and automated procedures suitable for a variety of cephalosporins are presented. Comparisons with other procedures and precision data are Included.

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