The use of a monolithic column to improve the simultaneous determination of four cephalosporin antibiotics in pharmaceuticals and body fluids by HPLC after solid phase extraction--a comparison with a conventional reversed-phase silica-based column

The use of a monolithic column (Chromolith, SpeedROD RP-18e, by Merck) was studied on the determination of cephalosporin antibiotics. Results were compared with those from a previously developed analytical method using conventional silica-based analytical column. A rapid, accurate and sensitive method has been developed and validated for the quantitative simultaneous determination of four cephalosporins: Cephalexine and Cephadroxil (first generation), Cefaclor (second generation) and Cefotaxim (third generation) in pharmaceuticals as well as in human blood serum and urine. Hydroflumethiazide (HFM) (3,4-dihydro-6(trifluoromethyl)-2H-1,2,4-benzothiadiazine-7-sulfonamide-1,1-dioxide) was used as an internal standard at a concentration of 1.5 ng/microL. A rectilinear relationship was observed up to 5 ng/microL for the four compounds. Analysis time was less than 4 min. The statistical evaluation of the method was examined by means of within-day repeatability (n=8) and day-to-day precision (n=8) and was found to be satisfactory with high accuracy and precision results. The method was applied to the determination of the cephalosporins in commercial pharmaceuticals and in biological fluids: human blood serum after solid phase extraction and urine simply after filtration and dilution. Recovery of analytes in spiked serum samples was in the range from 88.7 to 107.8%, while for urine samples recovery was from 98.0 to 105.6%. By comparing the figures of merit for the monolithic column and the silica-based one, regarding the determination of the four cephalosporins investigated in the present study, the outstanding efficiency of the monolithic column can be noticed.