Anthocyanin-Based Dispersive Liquid–Liquid Microextraction Based on Solidification of a Floating Organic Drop (DLLME–SFO) for Trace Pb(II) Determination in Water

An anthocyanin-based DLLME–SFO method utilizing a ligand-substitution strategy was investigated for the determination of Pb(II) in water samples using flame atomic absorption spectrometry (FAAS). A plant-derived anthocyanin extract from Clitoria ternatea was employed as a renewable ligand while 1-dodecanol served as the extraction solvent. Under optimized conditions, the method exhibited a linear range of 0.02–4.50 mg L−1 (r2 = 0.9948), with limits of detection and quantification of 0.0060 and 0.019 mg L−1, respectively. An enrichment factor of 20.2 was obtained, which is sufficient for trace analysis, along with good precision (intra-day and inter-day relative standard deviations (RSDs) of 1.2–2.8% and 2.5–4.3%, respectively). Spike–recovery experiments in natural water samples yielded recoveries of 94–106%, and statistical comparison with a reference wet digestion method showed no significant difference at the 95% confidence level (paired t-test, p > 0.05). Comparative evaluation with the conventional synthetic chelator 4-(2-pyridylazo)resorcinol (PAR) demonstrated comparable analytical performance, confirming that renewable anthocyanins can effectively substitute synthetic ligands without compromising extraction efficiency. The proposed method demonstrates a ligand-substitution strategy within a DLLME–SFO platform, integrating a biodegradable chelating agent with a microextraction system, and provides a greener approach for trace Pb(II) determination in environmental waters.