Analytical Sciences

Solid Phase Extraction and Spectrophotometric Determination of Silver with 2-(2-Quinolylazo)-5-diethylaminophenol as Chromogenic Reagent

Guangyu YANG,  Qiufen HU, Jihong YANG, Zhangjie HUANG, and Jiayuan YIN

Department of Chemistry, Yunnan University, Kunming 650091, P. R. China

A new chromogenic reagent, 2-(2-quinolylazo)-5-diethylaminophenol (QADEAP), was synthesized. A sensitive, selective and rapid method has been developed for the determination of ug/L level silver ion based on the rapid reaction of silver(I) with QADEAP and the solid phase extraction of the colored chelate with C₁₈ cartridge. The QADEAP reacts with Ag(I) to form a violet chelate of a molar ratio 1:2 (silver to QADEAP) in pH 3.5 - 8.0. This chelate was prconcentrated by solid phase extraction with C₁₈ cartridge. An enrichment factor of 100 was achieved. The molar absorptivity of the chelate is 1.30 x 10⁵ L mol^-1 cm^-1 at 590 nm in measured solution. Beer's law is obeyed in the range of 0.01 - 0.6 ug/ml. The relative standard deviation for eleven replicate samples of 0.01 ug/ml is 1.15%. The detection limit is 0.02 ug/L in the original samples. This method was applied to the determination of ug/L level silver ion in water with good results.

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