A simple and effective procedure for trace Pb(II) preconcentration and analysis in milk powders using alginate/chitosan/PVA composite as adsorbent

Keeping the sustainability concept in view, this work couples natural occurring materials, chitosan and alginate, and polivinylalcohol (PVA) to synthesize an Pb(II) efficient adsorbent (CAP) and describes a rapid preconcentration technique using syringe solid-phase extraction (SPE) for trace Pb(II). Subsequently, the CAP material was characterized by FTIR, XPS, and SEM-EDX. Several critical parameters were optimized, including pH value, CAP dose, sample and eluent cycle, HNO3 concentration as the eluent, preconcentration factor, selectivity, and reusability. To compare experimental parameter optimization with conventional methods, central composite design (CCD) was utilized to reduce factors. The optimum conditions were determined as follows: a sample solution pH of 5, a CAP mass of 100 mg, 5 cycles of sample and eluent, a maximum HNO3 concentration of 2 mol L–1, and a preconcentration factor of 100 times. Validation results with certified reference materials showed a very high Pb(II) recovery of 97.6 %. The method's limit of detection (LOD) was 4.19 µg L–1 with an RSD of 0.77 %. Under optimal conditions, the recovery of three milk powder samples ranged from 90.0 % to 98.4 %. The proposed syringe SPE procedure has been successfully applied to milk powder samples.