Method to Eliminate Fluoride Interference in the Spectrophotometric Estimation of Zirconium: Application to U-Zr...

In the estimation of Zr using the ultraviolet-visible (UV-Vis) spectrophotometric technique, fluoride interference is a decade-old unsolved problem. The process of repeated fuming with strong acids is often used to remove fluoride from the solution in order to estimate Zr using spectrophotometry analysis. For the first time, in this work, a simple use of AlCl₃ is reported as a suppressing reagent to eliminate the interference of fluoride in the estimation of Zr. Xylenol orange in HCl medium is used as a complexing reagent. Linearity in the datum acquired from absorbance at 551 nm (λ_max) is achieved over the concentration range 0.25-4.5 µg mL^-1 of Zr with a molar absorptivity of 35030 L·mol^-1·cm^-1 and Sandell's sensitivity of 0.003 µg·cm^-2. Zr is quantified in the variety of U-Zr alloys and various water samples using spectrophotometric detection with a classical univariate calibration with suppressing of fluoride interference through AlCl₃. Results from this novel analytical method herein developed for the first time are compared with those achieved from gravimetric analysis.