Cu 2 S-ZnS reduced graphene oxide nanocomposite for dispersive solid phase extraction of trace levels of Pb 2+ in water and rice samples followed by ETAAS

In this study, Cu2S–ZnS reduced graphene oxide (Cu2S–ZnS–rGO) nanocomposite was synthesized for the dispersive solid-phase extraction (DSPE) of trace levels of lead ion (Pb2+), followed by its determination using electrothermal atomic absorption spectrometry (ETAAS). The synthesized nanocomposite was characterized using X-Ray Diffraction (XRD) analysis, Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy (EDX) and Fourier Transform Infrared spectrophotometry (FT-IR). Key parameters influencing the extraction efficiency—including sample pH, adsorbent dosage, extraction time, and desorption conditions—were thoroughly optimized. Based on the results, the proposed method exhibited good linearity in the range of 0.10–8.0 μg/L, with a correlation coefficient (R2) of 0.9988. The limits of detection (LOD) and quantification (LOQ), calculated as 3Sb/m and 10Sb/m, were found to be 0.024 μg/L and 0.080 μg/L, respectively. The relative standard deviation (RSD) for six replicate measurements of a 1.0 μg/L Pb2+ solution was 4.3%. The adsorption mechanism was further investigated using adsorption isotherm models, which indicated that Pb2+ adsorption onto the adsorbent conformed to the Langmuir isotherm model, with a maximum adsorption capacity of 98.0 mg/g. Finally, the developed method was effectively employed to quantify trace amounts of Pb2+ in water and rice samples.