CoNiFe-LDH nanoflowers combined with bismuth-based layered perovskite oxide (Bi₂MoO₆) for vortex-assisted micro-solid phase extraction of lead from food and water samples.

Abstract

A new CoNiFe-LDH NFs/Bi₂MoO₆ nanocomposite was synthesized, characterized, and utilized to separate and enrich Pb(II) using vortex-assisted micro-solid phase extraction (SPE). The nanocomposite's high surface area and pH-dependent charge (PZC ≈ 6) enabled superior adsorption via electrostatic interactions, achieving >98 % recovery at pH 8. A preconcentration factor of 20 was obtained by optimizing the analytical parameters: 5 mg adsorbent, 20 mL sample volume, and 1 mL of 2 mol L-1 HNO₃ eluent. The VA-μSPE method showed high accuracy for intra-day and inter-day RSDs (7.8 % and 10.2 %, respectively) and low LODs (0.12-0.20 μg kg-1). Accuracy was validated using two SRMs with recoveries of 95-99 % and statistical agreement. Low environmental impact was obtained by sustainability evaluations using GAPI and WAC, which put a priority on energy efficiency and decreased reagent consumption. This study offers a green, sensitive, and accurate method for Pb(II) analysis in food and water samples.