Paper BM-TuP9
Capillary Electrophoresis Electrochemical Detector using Capacitometric Method for Endocrine Disruptor Detection

Tuesday, October 21, 2008, 6:30 pm, Room Hall D

Interests in the use of polymeric materials such as polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA) have increased over the past few years. PDMS has been widely discussed due to fine optical transparency for detection, curability at low temperatures, easily replicable molding and fine adhesion. In past, PDMS substrate based capillary electrophoresis-electrochemical detection (CE-ECD) microchips have been developed for separation and detection of endocrine disruptors. We also developed systems and measured bisphenol-A (BPA) and butylphenol as well as dopamine and catechol with various electrode structures such as ITO, Au as well as Prussian blue modified ITO and Au. Whereas, because of the sensitivity and structural dependence of measurement, capacitance based detection of these chemicals have not been attempted much so far. The strong point of the capacitometric method is that the electrode doesn’t need to be contacted with a sample or electrolyte, resulting in reproducible and more reliable results than those from the amperometric detection. Thus, as long as high sensitivity of capacitance can be achieved with a suitable detection system, we can apply it to even a flowing channel system. To do that, we used a high frequency cavity resonator and measured dC/dV with a resolution of better than 10-18 F/V. A device including microchannels built using PDMS mold was also fabricated on glass substrate. In this work, we studied capacitometric detection of BPA. The separation of BPA was carried out using a 7 cm long capillary. A solution containing MES of pH 6.5 was used as separation buffer. A field of 60 V/cm was applied to a channel for separation and the same field for injection for 10 seconds. With a time evolutional monitoring of dC/dV, 100 μM to 10 mM BPA could be detected.