title: Determination of ternary mixtures of antibiotics, by ratio-spectra zero-crossing first- and third-derivative spectrophotometry.
abstract: The ratio-spectra zero-crossing first- and third-derivative spectrophotometry have been used for determining ternary mixtures of penicillin-G sodium, penicillin-G procain and dihydrostreptomycin sulphate salts. The procedures are accurate, nondestructive and do not require resolutions of equations. In both methods, calibration graphs are linear, with zero-intercept, up to 30 micrograms ml-1 of penicillin-G sodium and penicillin-G procain, and up to 42 micrograms ml-1 of dihydrostreptomycin sulphate. r = 0.9999 in each instance. Working wavelengths, 218.5, 211 and 236 nm, respectively, in the first-derivative mode, and 222.5, 311.5 and 242 nm in the third-derivative mode. Detection limits for each drug at p = 0.01 level of significance were calculated to be 0.058, 0.010 and 0.014 micrograms ml-1 and 0.14, 0.012 and 0.34 micrograms ml-1, in the first- and third-derivative methods, respectively. Both methods apply favorably to either laboratory mixtures or commercial injections.
authors.affiliation: Università degli Studi Bari, Dipartimento di Chimica, BARI, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Morelli
mesh_terms: D004096:Dihydrostreptomycin Sulfate / Q000032:analysis / Q000737:chemistry; D004359:Drug Therapy, Combination / Q000032:analysis* / Q000737:chemistry; D007202:Indicators and Reagents; D010400:Penicillin G / Q000032:analysis / Q000737:chemistry; D010402:Penicillin G Procaine / Q000032:analysis / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007202:Indicators and Reagents; D010402:Penicillin G Procaine; D010400:Penicillin G; D004096:Dihydrostreptomycin Sulfate