Separation and determination of anesthetics by capillary electrophoresis with mixed micelles of sodium dodecyl sulfate and Tween 20 using electrochemiluminescence detection

A simple and new method for the simultaneous determination of procaine (Pro), lidocaine (Lid), ropivacaine (Rop) and bupivacaine (Bup) was developed using capillary electrophoresis separation with mixed micelles and electrochemiluminescence detection. The use of mixed micelles of 2.0 × 10^–3 mol/L sodium dodecyl sulfate (SDS) and 8.0 × 10^–3 mol/L Tween 20 greatly improved separation selectivity. The detection sensitivities of four drugs with a Pt working electrode were increased by modification of the Pt electrode with europium(III)–doped Prussian Blue analog (Eu–PB). Under optimal conditions, the four local anesthetics were well separated and detected. The limits of detection (LOD, S/N = 3) of Pro, Lid, Rop and Bup in standard solution are 2.5 × 10^–8, 1.3 × 10^–8, 3.0 × 10^–8 and 4.1 × 10^–8 mol/L, respectively. The limits of quantitation (LOQ, S/N = 10) of Pro, Lid, Rop and Bup are 2.3 × 10^–7, 1.2 × 10^–7, 3.7 × 10^–7 and 5.6 × 10^–7 mol/L in a human urine sample, and 8.5 × 10^–7, 6.9 × 10^–7, 2.8 × 10^–6 and 1.1 × 10^–6 mol/L in a human serum sample, respectively. The recoveries of four drugs at different spiked concentrations in human urine and serum samples were between 86.5 and 107.6%. The proposed method has been successfully applied to determine local anesthetics in biofluids. Copyright © 2012 John Wiley & Sons, Ltd.