Short-capillary electrophoresis with electrochemiluminescence detection using porous etched joint for fast analysis of lidocaine and ofloxacin

Fast analysis of ofloxacin and lidocaine, as bactericide and analgesic or anesthetics, is of clinic importance for understanding the patientʹs medical process. This paper presented a high throughput, simple analysis method of lidocaine and ofloxacin by capillary electrophoresis coupled with electrochemiluminescence (ECL) using porous etched joint. To shorten the analysis time and to improve the analytical performance, a capillary with 10 cm in length was used as the separation channel. The cyclic voltammograms of Ru(bpy)32+ with different capillary length at same field strength showed that the porous etched joint eliminated the effect of electrophoretic current on the ECL detection. Following micro total analysis systems (μTAS), some advantages of which this approach has, the fabrication of channel in chip was not needed. Compared with capillary electrophoresis with 40-cm-long capillary, the high sample throughput and low zone broadening may be the main advantage of the present system. Under optimal condition, the detection limits of lidocaine and ofloxacin based on peak height were 3.0 × 10−8 and 5.0 × 10−7 mol L−1 and a 60 h−1 of sampling frequency was obtained. The precision (R.S.D.) of the migration time and the peak height for five replicate injections of a mixture of lidocaine (1.0 × 10−6 mol L−1) and ofloxacin (4.0 × 10−6 mol L−1) were 3.2–3.9% and 4.7–5.3%, respectively.