Radionuclide and metal ion detection on a capillary electrophoresis microchip using LED absorbance detection

The sensitive and selective detection of various radionuclide, lanthanide and transition metal cations on a capillary electrophoresis (CE) microchip is demonstrated using two different metallochromic complexation ligands, 4-(2-pyridylazo) Resorcinol (PAR) and Arsenazo III (AIII). In order to take advantage of the compact and portable potential of a CE microchip, LED absorbance detection was investigated on a simple cross pattern microchip with two different microchannel depths, 20 and 100 μm. Micellar electrokinetic chromatography (MEKC) was utilized on a glass microchip to resolve up to seven different PAR–metal chelates with sub-ppm detection limits within a minute. Microchip determinations of U(VI) were performed using the colorimetric metal complexation ligand, Arsenazo III, utilizing absorbance detection with a red LED light source and a photodiode array detector. A mixture of UO22+ and three interference metal ions were separated on a microchip, and the addition of EDTA to the background electrolyte (BGE) is demonstrated to be an effective means of eliminating any interference from lanthanide and transition metal ions.