Utilizing the H-point Standard Addition Method for the Simultaneous Spectrophotometric Determination of Sulfadiazine and Trimethoprim in Binary Mixtures and Pharmaceutical Preparations

In this research, the H-point standard addition method was employed for simultaneous spectrophotometric determination of sulfadiazine (SDZ) and trimethoprim (TRM) in binary mixtures and therapeutic doses.The absorbance at 272 and 296 nm was monitored using standard solutions of sulfadiazine and trimethoprim, and the results showed that SDZ and TRM could be simultaneously determined at concentration ratios ranging from 1 -15 and 1-14 μg/mL, respectively.The recoveries were found to be 97.78-102.62% for SDZ and 97.7-102.8% for TRM, with a relative standard deviation (RSD) of ≤ 1.44% and ≤ 2.85% , respectively.The method was successfully applied to the determination of sulfadiazine and trimethoprim in their binary formulations of pharmaceutical preparations with accept able accuracy and good recoveries.