Determination of diastereoisomeric alkaloids in urine by capillary electrophoresis with electrochemiluminescence detection

A new and simple capillary electrophoresis with electrochemiluminescence detection was developed for the separation and the quantification of a pair of diastereoisomeric alkaloids (ephedrine and pseudoephedrine). The limits of detection (S/N = 3) were 4.5 × 10 −8 mol/L for ephedrine and 5.2 × 10 −8 mol/L for pseudoephedrine, respectively. The RSDs of migration time and peak area were less than 1.3 and 2.5% ( n = 5), respectively. The applicability of the propose method was illustrated in the determination of ephedrine and pseudoephedrine in human urine, ephedrine in nasal drops, and the monitoring of pharmacokinetics for pseudoephedrine.