Solid phase extraction spectrophotometric determination of zinc in water sample with 2-(2-quinolinylazo)-4-methyl-1,3-dihydroxybenzene as chromogenic reagent

The color reaction of 2-(2-quinolinylazo)-4-methyl-1,3-dihydroxybenzene (QAMDHB) with zinc(Ⅱ) was studied. In the presence of TritonX-100 and in the medium of pH 8.5 buffer solution, QAMDHB can react with zinc(Ⅱ) to form a stable 2∶1 complex, which apparent molar absorptivity is 8.84×104 L·moL-1·cm-1 at 565 nm. Beer's law is obeyed in range of 0.01-1.0 μg/mL for zinc. The zinc ion in samples can be enriched and separated by solid phase extraction with anion exchange resin cartridge,followed by reverse elution with 6 mL water, at last determined by spectrometry. The relative standard deviations are 2.2%, 2.4%. The standard recoveries are 103%, 97%. The determination results are agreed with those of AAS method.