Simultaneous determination of norfloxacin and sulfadiazine by first-derivative spectrophotometry

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 ۲۴۰ and ۲۹۰ 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 ۲۵۷ nm, and showed linearity in the range ۳.۲ ۱۰-۶ – ۳.۲ ۱۰-۵ M, whereas SDZ was determined at a λmax of ۲۷۲ nm, and it showed linearity in the range of ۳.۰ ۱۰-۶ – ۳.۰ ۱۰-۵ M. In both cases, the correlation coefficient was ۰.۹۹۹ (R۲). 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 ۱.۰۹ ۱۰-۷ M and the limit of quantification was ۳.۳۱ ۱۰-۷ M. SDZ limit of detection was ۵.۱۴ ۱۰-۷ M and the limit of quantification was ۱.۵۶ ۱۰-۶ M. The accuracy of NF and SDZ was more than ۹۸.۹۱% and ۹۹.۰۱%, respectively. The results obtained indicate that the proposed methodology is suitable for the simultaneous determination of NF and SDZ in solution.

Keywords:

Derivative Spectrophotometry , Zero-crossing , Simultaneous determination , Norfloxacin , Sulfadiazine