Modification of Gold Nanoparticle Loaded on Activated Carbon with Bis(4-methoxysalicylaldehyde)-1,2-Phenylenediamine as New Sorbent for Enrichment of Some Metal Ions

In this study, a new sorbent based on the gold nanoparticle loaded in activated carbon (Au-NP-AC) was synthesized and modified by bis(4-methoxy salicylaldehyde)-1,2-phenylenediamine (BMSAPD). This sorbent, which is abbreviated as Au-NP-AC-BMSAPD, has been applied for the enrichment and preconcentration of trace amounts of Co²⁺, Cu²⁺, Ni²⁺, Fe²⁺, Pb²⁺, and Zn²⁺ ions in real samples. All metal ions under study were retained on the Au-NP-AC-BMSAPD sorbent by complexation of the ions with the BMSAPD ligand, providing an efficient preconcentration fashion. The retained metal ions were then eluted from the sorbent by HNO₃ and detected by flame atomic absorption spectrometry. The analytical parameters including pH, amount of ligand, and the nature of the eluent and solid phase were evaluated to obtain the optimum condition for the preconcentration factor. Following the optimum conditions, a preconcentration factor of 200 was obtained for all the metal ions under study with detection limits of 1.4–2.6 ng mL⁻¹. The method has been successfully applied for the extraction and determination of the ion content in the same real samples with recoveries in the range of 95–99.6% and a relative standard deviation lower than 4.0%.