Fast preconcentration of Pb(II) and Cu(II) in liquid milk by syringe solid-phase extraction using alginate and PVA...

The simultaneous preconcentration and determination of Pb(II) and Cu(II) was afforded by a Syringe Solid Phase Extraction (SSPE) technique, which was developed and described for the first time, exploiting the alginate/carbon/PVA (ACP) sorbent as a support material. Imperative experimental factors were appraised in detail: pH 5.0 for Pb(II) and 4.0 for Cu(II), 75 mg of ACP mass, 4 sample cycles, 9 eluent cycles for Pb(II), 8 eluent cycles for Cu(II), and 1 mol L^-1 of HNO₃ as the eluent were found to be the optimal conditions for the devised procedure. The preconcentration factors were found to be 100 for both Pb(II) and Cu(II). These optimal conditions closely align with those obtained from the Box-Behnken Design (BBD) optimization. The results confirmed that ACP as the adsorbent could be reused up to 8 times. The LOD values calculated for Pb(II) and Cu(II) were 9.34 and 7.17 μg L^-1, respectively. The calculated RSDs were less than 3.3%. The validated recoveries by ERM-BD151 (standard reference sample) were acquired at 97.6% for Pb(II) and 98.9% for Cu(II). The approach designed for the preconcentration of analytes in liquid milk samples proved successful.