2004 Volume 20 Issue 6 Pages 955-959
A selective and sensitive derivative photometric method has been developed for the determination of trace amounts of Zn2+ with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the presence of cetylpyridinium chloride, a cationic surfactant. The molar-absorption coefficient and analytical sensitivity of the 1:2 complex at 554 nm are 1.19 × 105 L mol-1 cm-1 and 0.56 ng mL-1, respectively. The detection limit is 1.96 × 10-2 ng mL-1 and Beer’s law is valid in the 0.02 - 0.66 µg mL-1 range of Zn2+. The developed derivative procedure, using the zero-crossing measurement approach, is applied for the rapid and selective simultaneous determination of Zn2+ and Cd2+ in the range of 0.06 - 0.66 and 0.20 - 1.60 µg mL-1, respectively. Complex matrices, including reference materials, environmental and biological samples and synthetic mixtures, have been successfully analyzed for trace amounts of the two metal ions.
