Electrochemical determination of DNA using flow injection analysis

6 Abstract The aim of this work was to create a method for electrochemical detection of DNA in a flow system and subsequently evaluate its functionality and usability. Prior to actual measurement in the flow system, an evaluation of a suitable type of working electrode was performed in a batch measurement, where a basal plane pyrolytic graphite electrode (BPPGE) was selected from the evaluated types of working electrodes. For signaling the sample zone on the surface of the working electrode in the flow arrangement, the recording of the dependence of the first derivative of current response with respect to time (dI/dt) was tested. For this measurements, a flow rate of 0,4 ml·min−1 was evaluated as optimal conditions, using a 0,35 mm-thick PTFE spacer film with a volume of 1,5 µl above the working electrode and a time delay prior stopping the flow 0,5 s after exceeding the set threshold of the dependence of dI/dt with respect to time. During the repeatability check of the procedure for automatic stopping of the sample zone on BPPGE, instability of acetate buffer noise (pH 5) was found, which greatly complicated long-term use of the procedure, and an alternative method of dispensing was therefore sought. For this purpose, a new 3D printed electrochemical cell with a dispensing hole directly into the cell..