Document Abstract
A simple and highly selective surfactant assisted kinetic spectrophotometric method for the determination of
thallium has been developed. The method is based on the quantitative oxidation of Tl(I) to Tl(III) using bromine
water where the resulting Tl(III) liberated iodine from potassium iodide in acidic medium. The liberated iodine
was subsequently reactedwith I−ion to formtri-iodide ions (I3
−). The tri-iodide ions formedwere further reacted
with cetylpyridinium cation (CP+) which produced a violet ion associate species having a λmax of 512 nm
at which reaction was monitored. The reaction variables such as time, temperature, reagent concentration and
acidity were optimized for the indicator reaction to achieve maximum sensitivity. The linear regression calibration
concentration range of 0.007–0.1 μgmL−1 Tl(I) was established as the Beer's law was obeyed in this range.
Sandell's sensitivity and molar absorptivity of the ion associate species in terms of thallium were determined to
be 0.000133 μg cm−2 and 1.99 × 106 L mol−1 cm−1 respectively. The limit of detection was determined
as 0.0029 μgmL−1. The developed method has successfully been applied for the determination of thalliumin different
environmental samples with satisfactory results