Dispersive solid phase extraction of lead in water samples using embedded 1,5-diphenylcarbazone grafted graphene oxide in microporous magnetic chitosan coupled with flame atomic absorption spectrometry

Abstract

In the current study, an embedded 1,5-diphenylcarbazone (DPC) grafted graphene oxide (GO) in porous magnetic chitosan (MC) nanocomposite was synthesized and used for preconcentration of trace amount of Pb(II). For this purpose, a magnetic dispersive solid phase extraction (MDSPE) was utilized prior to determination by flame atomic absorption spectrometry (FAAS). The adsorbent was characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The parameters influencing the extraction efficiency such as pH, extraction and desorption time, adsorbent amount and type, concentration and volume of eluent were optimized by design of experiment. Under the optimum conditions, calibration curve was linear within the range of 3.0–300 ng mL⁻¹ with regression coefficient of 0.9957. The enhancement factor was obtained as 13.5 corresponding to the absolute recovery of 81%. The limits of detection (LOD, 3S_b/m) and quantification (LOQ) were found to be 0.13 ng mL⁻¹ and 0.43 ng mL⁻¹, respectively. Intra- and inter-day precisions (n = 5) were estimated using the relative standard deviation (RSD%) at three concentrations of 25, 100 and 250 ng mL⁻¹ and were less than 3.2% and 5.6%, respectively. The maximum adsorption capacity (q_m), calculated by the Langmuir equation, was found to be 57.47 mg g⁻¹. The method was validated by analysis of an SRM-1643f standard reference material for trace elements in water. Finally, the method was successfully applied for the determination of trace amount of Pb(II) in various water samples with good relative recoveries ranged from 92.3 to 105%.