Dispersive micro-solid-phase extraction using chitosan/polymethacrylate/clay bionanocomposite followed by UV–Vis spectrophotometry for determination of zinc

A novel chitosan-poly(methacrylate)-clay (CTS-pHEMA-MMT) superabsorbent bionanocomposite was prepared by radical copolymerization method and characterized by Fourier-transform infrared spectroscopy, thermal gravimetric analysis, X-ray diffraction analysis and scanning electron microscopy. The CTS-pHEMA-MMT composite was applied as a sorbent in dispersive micro-solid-phase extraction (D-µ-SPE) of zinc before its spectrophotometric determination after eluting with 4-(2-pyridylazo) resorcinol solution. Under the optimized experimental conditions, the developed D-µ-SPE method with aqueous standard Zn solutions presented a linear working range from 10 to 1000 ng mL −1 with a correlation coefficient of 0.996, a detection limit of 3.1 ng mL −1 and a relative standard deviation better than 3.5% ( n = 5) for 10 ng mL −1 and 50 ng mL −1 of Zn(II). The preconcentration factor and the sorption capacity of the synthesized sorbent for zinc were 100 and 5.04 mg g −1 , respectively. The recoveries for zinc in tap water, drinking water, milk, butter, and vitamin tablet samples were obtained in the range of 93.7–102.5% for spiked 10 ng mL −1 and 50 ng mL −1 of Zn(II).