Synthesis and Spectrophotometric Study of 4-(6- Bromo -2-benzothiazolylazo)phloroglucinol as an Analytical Reagent for Determination of Bismuth.


AbstractA new chromogenic reagent, 4-(6-Bromo-2-benzothiazolylazo)phloroglucinol (6-BrBTAPG), was synthesized by diazo coupling of(2-amino-6-bromo benzothiazol) (2-ABrBT) with phloroglucinol, and used for the spectrophotometric determination of bismuth (III).This method was simple, sensitive, selective and rapid for reaction between Bi3+ and (6-BrBTAPG),to form a pink complex having a molar ratio of (1:1) (Bi-6-BrBTAPG) at pH 7.5. The molar absorptivity of the complex was 0.2654×104 L.mol-1 cm-1 at  max 538 nm. Beer’s law is obeyed in the range of (0.5–30) ppm of bismuth ,and the stability constant was found to be 3 × 104 L.mol-1.The relative standard deviation for seventh replicate measurements ,recovery ,and relative error values of this method were found to be 0.736 , 101.33, and1.33 respectively . The interference of foreign ions was also investigated. All the other ions studied did not interfere with bismuth determination except for Mn2+ , Co2+,Fe3+,V5+,and pb2+. The interferences were eliminated approximately using suitable masking agent .