Development of analytical method for selective enrichment and determination of trace Pb(II) and Cd(II): experimental...

The preconcentration of trace metal ions using nanosorbents is often hindered by uncontrolled sample penetration, structural imperfections, and poor hydrophilicity. In this study, oxygenated carbon nitride were uniformly deposited onto alumina to construct a solid-phase extraction column for ultra-trace metal analysis. The sorbent exhibited excellent selectivity and preconcentration limit toward target ions and achieved exceptionally low detection limit of 0.02 ng mL^-1, with negligible interference from coexisting ions. Method validation using the standard addition approach confirmed accuracy at the 95% confidence level (t_calculated < 4.303), while precision remained high, with coefficients of variation between 3 and 4.5%. Machine learning models were applied to interpret adsorption behavior, with the random forest algorithm showing the best predictive performance. Key influencing parameters included ionic radius, electronegativity, sorbent mass (dosage), pH, initial concentration, contact time, surface charge/zeta potential, and temperature. The developed SPE column provides rapid and reliable method for trace metal determination in food samples.