Utilization of Cloud Point Extraction in Spectrophotometric Determination of Terbutaline Sulfate Using Diazotization and Coupling Reaction..

A simple, accurate, and efficient cloud point spectrophotometric method, characterized by compatibility and sensitivity, has been described for the estimation of terbutaline sulfate (TbS) in its pure and pharmaceutical formulation as syrup. The procedure was dependent on the reaction of TbS and diazotized 2,4-dinitroaniline (2,4-DNA) in a basic medium, resulting in the formation of an orange azo dye product, which was extracted into Triton x-114 micelles and measured at 448 nm. The conditions of phase separation were studied and optimized. Beer's law was obeyed at concentration ranges of 0.113 g/ml with a molar absorptivity of 1.6106 L. mol-1. cm-1. The limit of detection (LOD) and limit of quantitation (LOQ) were determined and found to be 0.04 and 1.14 g/ml, respectively, and the average recovery % is 98.91%. The relative standard deviation (RSD) was calculated and found 1.6%. It was also found, through studying the nature of the product, that the azo dye product is formed in a 1:1 ratio of TbS to 2,4-DNA. The method was applied successfully for the determination of TbS in syrup and was free from interference by excipients. The reaction mechanism has been suggested.