Monolithic capillary column with integrated electrochemical detector

Abstract

Fast and simple quantification of neurotransmitters in biological samples plays crucial role in diagnostic of several neurological diseases, for example depression, Parkinson’s disease, and others. A combination of monolithic capillary columns and electrochemical detection offers an elegant way in the preparation of miniaturized, cheap and portable analytical systems. Here we show miniaturization and integration of an electrochemical detector. Microelectrodes were glued to copper wire and then integrated into monolithic capillary column. Carbon fibers with diameter 7 μm and different surface treatment (epoxy sized and unsized) were used as working microelectrodes. As a reference microelectrode, either carbon fiber with coated metallic silver or silver microwire (diameter 25 μm) was employed. The final arrangement of detector utilized silver microwire as a reference electrode, which possessed better potential, chemical and mechanical stability in time, and unsized carbon fiber as a working electrode. Prepared electrochemical detector was characterized by amperometric detection of dopamine solutions. Detection limit of 110 pg of injected dopamine was achieved. Monolithic capillary column with integrated electrochemical detector was used for analysis of standards of neurotransmitters. Currently, the capabilities of prepared device are tested in analysis of dopamine in urine. Integrated monolithic capillary column is one of the first steps in the development of miniaturized analytical systems providing chromatographic separation with use of polymer monoliths and electrochemical detection. Such systems can be employed for a personalized medicine allowing reduction of both time and financial costs.