Extraction-Spectrophotometric Determination Of Certain-?-Lactam Antibiotics With Methylene Blue
An extraction-spectrophotometric method was established for the determination of certain Î²-lactams, cefaclor, ampicillin and amoxycillin in pure and dosage forms using methylene blue (MB) as an analytical reagent. The method is based on the formation of a chloroform-extractable blue colored ion-association complex (MB cation-antibiotic anion) through the reaction of a Î²-lactam antibiotic with an excess of methylene blue at pH 9.5. Good agreement with Beer's law was found in the range of antibiotic concentration of 3.5-90.0 Î¼g/ml with a detection limit of 3.0 Î¼g/ml. The method is simple, precise and accurate for pure analyte with excellent recovery (97-102%); and also, this does not require any separation of soluble excipients in pharmaceutical preparations.