Thin layer resin phase spectrophotometric determination of trace bismuthIII in water sample

A new method for the determination of Bi in water sample by thin layer resin phase spectrophotometry was developed. Bi with I~- forms a complex anion of [BiI_4]~-, which can exchanges and associates with Cl~- on the surface active sites of anion exchange resin (R~+) of 717 type to form an association system of (R~+)-[BiI_4]~-. The maximum absorption wavelength of the system was located at 460 nm. The thin layer resin phase spectrophotometry gives a apparent molar absorptivity of (e_ 460 ) 7. 1×10~5 L·mol~ -1 ·cm~ -1 , which is about 18 times higher than in water phase(e_ 460 = 3.9×10~4 L·mol~ -1 ·cm~ -1 ). It had an ideal precision (0.5 μg/mL Bi, n=6, RSD = 1.82%). The detection limit of Bi in aqueous solution is 1.4×10~ -8 mol/L, and Beer's law is obeyed in the range of 0-1.2 μg/mL for Bi. Bi was determined in natural water with recovery of 96%-103%, and the determination results are agreement with those of atomic absorption spectrometry.