Laser-Induced Fluorescence Detection of Copper Ion With a Rhodamine Derivative by a Capillary Electrophoresis Microchip

A capillary electrophoresis microchip system with a confocal LIF detector was successfully constructed. RBPhOH, a new fluorescence dye synthesized from rhodamine B, was first investigated in a glass microchip for the selective and sensitive determination of copper ion by LIF method. The influences of the pH value, concentration of running buffer, detection voltage, and sample loading time on the response of LIF detector were studied. RBPhOH dissolved in 20 mM pH 6.0 Tris containing 10% acetonitrile could detect copper ions with a detection limit of 1.34×10⁻7 mol L⁻¹ (S/N=3), an order of magnitude lower than those of conductivity detectors.