title: Determination of Ro 14-1761, a new third-generation cephalosporin, in the plasma and milk of cattle by column switching high-performance liquid chromatography.
abstract: A sensitive and specific high-performance liquid chromatographic procedure was developed for the determination of the third-generation cephalosporin Ro 14-1761 in cow plasma and milk. The molecular structure of the new antimicrobial was very close to that of ceftriaxone, but the high-performance liquid chromatographic methods available for the latter could not be used as Ro 14-1761 adsorbed and/or degraded during the chromatographic process. Furthermore, the high-performance liquid chromatographic technique derived for ceftriaxone was not sensitive enough for our purposes. In the new assay, the plasma (milk) protein was precipitated with acetonitrile after dilution of the sample with water. For low concentrations (less than or equal to 10 micrograms/ml), the supernatant obtained after centrifugation was concentrated by extracting acetonitrile with methylene chloride. Quantification was performed by column switching high-performance liquid chromatography with UV detection (274 nm) using ion-pair reversed-phase chromatography. Ethylenediaminotetraacetic sodium salt had to be added to the mobile phase (1.2 mM) to prevent adsorption and/or degradation of the cephalosporin on the analytical column. The selectivity of the chromatographic separation was enhanced by heating the column to ca. 50 degrees C. The drug recovery was better than 85%. The limit for quantitative determination in both milk and plasma was 0.1 microgram of Ro 14-1761 per millilitre with an accuracy of 1% (coefficient of variation 10%). The overall accuracy and precision were 1-10% in the 0.1-100 micrograms/ml concentration range.
mesh_terms: D000818:Animals; D002417:Cattle; D002443:Ceftriaxone / Q000032:analysis* / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D004492:Edetic Acid; D007202:Indicators and Reagents; D008892:Milk / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007202:Indicators and Reagents; D002443:Ceftriaxone; C049927:Ro 14-1761; D004492:Edetic Acid