[Study on solid phase extraction and spectrophotometric determination of cadmium with 2-[2-(5-bromoquinolinylazo)]-5-diethylaminophenol].

A new chromogenic reagent 2-[2-(5-bromoquinolinylazo)]-5-diethylaminophenol (5-Br-QADEAP) was synthesized, and its structure was verified by elemental analysis, infrared spectrum, and 1H nuclear magnetic resonance spectrum. The color reaction of 5-Br-QADEAP with cadmium was studied. In the presence of pH 8.0 buffer solution and Triton X-100 medium, 5-Br-QADEAP can react with cadmium(II) to form a stable 2 : 1 complex (5-Br-QADEAP: Cd(II). The molar absorptivity is 1.60 x 10(5) L x mol(-1) x cm(-1) at 595 nm. Beer's law is obeyed in the range of 0-1.0 microg x mL(-1). The cadmium ion in the samples can be enriched and separated by solid phase extraction with anion exchange resin cartridge. This method was applied to the determination of cadmium in water and food. The relative standard deviations are 2.5%-3.2%, and the recoveries are 96%-105%. The results are satisfactory.