Simultaneous determination of pethidine and methadone by capillary electrophoresis with electrochemiluminescence detection of tris(2,2′-bipyridyl)ruthenium(II)

In this paper, we described a simple and rapid method, capillary electrophoresis with electrochemiluminescence (CE-ECL) detection using tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)(3)(2+)), to simultaneously detect pethidine and methadone. Analytes were injected to separation capillary of 67.5 cm length (25 mu m i.d., 360 mu m o.d.) by electrokinetic injection for 10 s at 10 kV. Under the optimized conditions: ECL detection at 1.20 V, 30 mM sodium phosphate (pH 6.0) as running buffer, separation voltage at 14.0 kV, 5 mM Ru(bpy)(3)(2+) with 50 mM sodium phosphate (pH 6.5) in the detection cell, the linear range from 2.0 x 10(-6) to 2.0 x 10(-5) M for pethidine and 5.0 x 10(-6) to 2.0 x 10(-4) M for methadone and detection limits of 0.5 mu M for both of them were achieved (S/N=3). Relative standard derivations of the ECL intensity were 2.09% and 6.59% for pethidine and methadone, respectively. (C) 2008 Elsevier B.V. All rights reserved.