Off-Column Amperometric Detection for Pressurized Capillary Electrochromatography
A system enabling coupling of pressurized capillary electrochromatography (pCEC) with off-column amperometric detection (AD) is reported in which conduction of the current in pCEC was achieved through a cellulose acetate-coated porous polymer joint, and the effect of the high-voltage field applied to pCEC for AD was also eliminated. Effects of supplementary pressure on the porous polymer joint and the effects on AD of capillary columns of different i.d. were investigated. The performance of the pCEC–AD system with the porous polymer joint was evaluated with phenol and hydroquinone using sulfonated stearyl methacrylate monolithic columns. The separation efficiency of the column in pCEC–AD, using the proposed off-column detection with the cellulose acetate membrane joint, was comparable with that of pCEC–UV using on-column detection. Compared with end-column detection using a 50 μm i.d. capillary column without a joint, a higher signal-to-noise ratio was achieved, even using a 100 μm i.d. capillary column with a joint. Successful separation and detection of dopamine and epinephrine were also achieved by use of this system.
KeywordsCapillary electrochromatography Off-column Amperometric detection
This work was supported by funding from the National High-Tech R&D Program (2006AA09Z161), the National Natural Science Foundation of China (20907009, 40976071), the Science Foundation of Fujian Province (2007J0129), the Key Science and Technology Project of Fujian Province (2007Y0062, 2007Y0022, 2008Y2004), the Science and Technology Project of Fuzhou University (2008-XQ-06), and the fund of Key Laboratory of Chinese Pharmacies for Fujian University (CKJ2008027).