Sensitive spectrophotometric determination of thallium(i)using rhodamine B hydrazide in micellar medium

A simple, sensitive, and rapid spectrophotometric method is proposed for the determination of the trace amount of thallium. The method is based on the oxidation of rhodamine B hydrazide by thallium(I) in acidic medium to give a pinkish violet radical cation, having a maximum absorption at 565 nm. The sensitivity of the method was found to increase when performed in micellar medium. Beer's law is valid over the concentration range of 0.005 μg mL−1 to 6.4 μg mL−1 with molar absorptivity and Sandell's sensitivity of 6.305 × 104 L mol−1 cm−1 and 0.008 mg cm−1 respectively. The tolerance limits for interfering ions are discussed. All variables were studied in order to optimize the reaction conditions. The validity of the method was checked by its simultaneous determination in synthetic samples.