Multilayer Thin Film Electrode for HPLC Detectors

Microbore HPLC is a very useful technique for analyzing small volume neurochemical extracts, but electrochemical detection has been difficult to implement in the restricted microbore environment. The goal of the contract is to develop a tubular ultramicroelectrode array for use in a detector directly attached to the end of the column to eliminate post- column dispersion of eluent components before detection. The electrode is designed to be rugged and capable of in stiu electrochemical cleaning to overcome potential problems from electrode fouling. Our previous work demonstrated that single element ultramicroelectrodes have amperometric responses proportional to concentration and independent of flow rate over a wide range, but the area definition and stability of the electrodes were inadequate for a commercial analytical device. New materials and fabrication techniques are proposed to overcome these problems and lead to a low-cost "throw-away" detector. In Phase I, we will fabricate single and multielement microband electrodes and demonstrate their stability and ability for high sensitivity detection and flow independent amperometric response toward a model redox species and a biogenic amine. Phase II will incorporate these detectors into commercial HPLC instruments and test their performance with model compounds and neurotransmitters injected into microbore columns. The software will also be developed for us suing the multilayer detector with sample mixtures.