COLORIMETRIC DETERMINATION OF PENICILLINS AND RELATED COMPOUNDS IN INTRAVENOUS SOLUTIONS BY NICKEL(II)-CATALYZED HYDROXAMIC ACID FORMATION

Solutions of ampicillin, carbenicillin, methicillin, oxacillin, penicillin G, and cephalothin in 5% dextrose were analyzed by nickel(II)‐catalyzed hydroxylaminolysis. The reactions of these antibiotics were complete within 20 min at room temperature. Under the analytical conditions, molar absorptivities of the ferric‐hydroxamate complexes ranged from 830 to 1005 liters/mole/cm. Coefficients of variation for the analysis of these antibiotics in 5% dextrose were typically <3% at concentrations of 1 mg/ml. Oxacillin was analyzed by the same method in normal saline and/or lactated Ringer solutions. The method also was applied to the analysis of chloramphenicol in aqueous solutions. Only ampicillin showed a significant decrease in concentration in 48 hr. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company