Simultaneous determination of norfloxacin and sulfadiazine by first-derivative spectrophotometry

Document Type : Research Article


1 1GQM-CRIDECIT, Facultad de Ciencias Naturales y Ciencias de la Salud, Universidad Nacional de la Patagonia San Juan Bosco, Ciudad universitaria, Km. 4, Ruta Prov. N° 1, (9000), Comodoro Rivadavia, Chubut. Argentina

2 Departamento de Ciencias Farmacéuticas, Medina Allende y Haya de la Torre, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, (5000) Córdoba. Argentina


In the present study, the development and validation of a UV-Vis spectrophotometry technique are described, applying the first derivative for the simultaneous determination and quantification of norfloxacin (NF) and sulfadiazine (SDZ). Since zero-order UV absorption spectra of both drugs overlap in the region between 240 and 290 nm, the first-order derivative strategy was selected, measured as "zero-crossing". This technique has the advantage of being simple, low-cost, and fast. The guidelines of the International Conference on Harmonization were followed. NF was determined at a λmax of 257 nm, and showed linearity in the range 3.2 10-6 – 3.2 10-5 M, whereas SDZ was determined at a λmax of 272 nm, and it showed linearity in the range of 3.0 10-6 – 3.0 10-5 M. In both cases, the correlation coefficient was 0.999 (R2). The methodology was statistically validated by evaluating the following parameters: limit of detection and quantification, precision (repeatability and intermediate precision), specificity, and accuracy. NF limit of detection was 1.09 10-7 M and the limit of quantification was 3.31 10-7 M. SDZ limit of detection was 5.14 10-7 M and the limit of quantification was 1.56 10-6 M. The accuracy of NF and SDZ was more than 98.91% and 99.01%, respectively. The results obtained indicate that the proposed methodology is suitable for the simultaneous determination of NF and SDZ in solution.


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