Establishment of a new dispersive solid phase microextraction method with a green adsorbent CaAl-LDH hybrid with g-C3N4 for the determination of Pb2+ in instant cup noodles and environmental samples

Abstract

Adsorbents with significant adsorption capacity and high selectivity are required to identify and eliminate heavy metal ions from the environmental and food samples under study. For this purpose, in the present work a new adsorbent, graphitic carbon nitride g-C₃N₄ hybrid with CaAl layered double hydroxide, was effectively synthesised using an easy hydrothermal co-precipitation procedure and applied for Pb²⁺ determination in food and water samples using dispersive solid phase-microextraction (DSP-µE) via FAAS. The as synthesized CaAl-LDH@g-C₃N₄ nanocomposite characteristics were examined using XRD, SEM, SEM-EDX and FTIR. Significant analytical parameters were optimised such as pH 8, adsorbent quantity 10 mg, and adsorption and elution times 30 and 60 s, respectively. Additionally, a sample volume of 20 mL and an eluent volume of 2 mL were used with an elution solvent of 0.5 M HNO₃. A matrix effect study was also performed as verification of the developed method. A limit of detection (LOD) of 0.54 µg L⁻¹, a limit of quantification (LOQ) of 1.79 µg L⁻¹, an enrichment factor (EF) of 10.69 and a preconcentration factor (PF) of 10 were determined. The % RSD (< 10%) with an R² value of 0.999 has proven the linearity and high accuracy of the developed method. ComplexMoGAPI evaluation (score 79) confirmed the excellent greenness of the proposed method. Standard reference materials (SRMs) were used to affirm the accuracy of the method. Different instant noodle samples, and tap water samples were analysed for their Pb²⁺ content, allowing for the successful determination of Pb²⁺ levels in them.