Innovative Design and Fabrication of Monolithic Columns Inside Microchip Devices for Determination of Ni(II) Ions

An innovative system was developed by fabricating a polymer-based monolith as an effective cation-exchange column within a glass microchip, achieved through in situ polymerization of glycidyl methacrylate (GMA), acrylic acid (AAc), and acrylamide (AAm) via free radical polymerization. Epoxy rings on the monolith surface were subsequently sulfonated with Na2SO3 at 70°C to form (R-SO3Na) groups. The microchip was integrated with a modified HPLC system equipped with a 3-way sub-valve (25 μL), allowing for the reagent-injection of the imidazole-azo ligand MPDADPI to react with Ni(II) ions and form a colored complex at 513 nm within 30 seconds. The calibration curve followed Beer’s law over the range of 0.001–3.5 μg mL-¹ (R² = 0.9977). Limits of detection (LOD) and quantification (LOQ) were 0.87 and 2.87 ng mL-¹, respectively. The method was validated using atomic absorption spectrophotometry (AAS).An innovative system was developed by fabricating a polymer-based monolith as an effective cation-exchange column within a glass microchip, achieved through in situ polymerization of glycidyl methacrylate (GMA), acrylic acid (AAc), and acrylamide (AAm) via free radical polymerization. Epoxy rings on the monolith surface were subsequently sulfonated with Na2SO3 at 70°C to form (R-SO3Na) groups. The microchip was integrated with a modified HPLC system equipped with a 3-way sub-valve (25 μL), allowing for the reagent-injection of the imidazole-azo ligand MPDADPI to react with Ni(II) ions and form a colored complex at 513 nm within 30 seconds. The calibration curve followed Beer’s law over the range of 0.001–3.5 μg mL-¹ (R² = 0.9977). Limits of detection (LOD) and quantification (LOQ) were 0.87 and 2.87 ng mL-¹, respectively. The method was validated using atomic absorption spectrophotometry (AAS).