Pectic acid–graphene oxide nanocomposite as an adsorbent in vortex-assisted dispersive solid-phase extraction for preconcentration of copper ion followed by flame atomic absorption spectrometry.

An efficient, green, novel and rapid vortex-assisted dispersive solid-phase extraction (VADSPE) technique was used for the preconcentration and determination of trace levels of Cu²⁺ followed by flame atomic absorption spectrometry. Graphene oxide (GO) was synthesized from graphite and then modified by pectic acid (poly-d-galacturonic acid, PA) to synthesize the pectic acid–graphene oxide (PA-GO) nanocomposite. The Fourier transform infrared spectrophotometry, field emission scanning electron microcopy, energy-dispersive X-ray spectroscopy and X-ray diffraction analysis were used to characterize the synthesized GO-PA nanocomposite. By using VADSPE technique, PA-GO was used as an adsorbent for preconcentration of Cu²⁺. The main parameters affecting the extraction recovery, including pH of the sample solution, amounts of adsorbent, extraction time, type and concentration of desorbent solvent and desorption time were completely investigated and optimized. Under the optimum conditions, the results show that the proposed method has the linearity range of 10–300 µg L⁻¹ with a correlation coefficient of 0.9950. The limit of detection based on six replicate analyses of the blank sample was 2.22 µg L⁻¹, and the relative standard deviation was 2.7% for the five replicate analysis of 50 µg L⁻¹ Cu²⁺. The validity of the proposed method was checked by the analysis of two certified reference materials including CRM-TMDW and GBW07605 tea samples, and then, the proposed method was successfully applied for the determination of trace levels of Cu²⁺ in different water and food samples. [ABSTRACT FROM AUTHOR]