Determination of levodopa methyl ester and its metabolites in rat serum by CZE with amperometric detection.
A reliable and reproducible method, capillary zone electrophoresis with amperometric detection (CZE-AD), has been developed for separation and quantification of levodopa methyl ester (LDME) and its biotransformation products levodopa (L-DOPA) and dopamine (DA) in rat serum. A carbon-disk electrode was used as working electrode. The optimum conditions for CZE detection were 50 mmol L(-1) phosphate solution at pH 7.0 as running buffer, 17 kV as separation voltage, 1.0 V (vs Ag/AgCl, 3.0 mol L(-1)) as detection potential, and sample injection for 8 s at 17 kV. The linear ranges were from 2.4 x 10(-2) to 2.2 microg mL(-1) for LDME, 2.9 x 10(-1) to 49.5 microg mL(-1) for L-DOPA, and 1.4 x 10(-2) to 1.5 microg mL(-1) for DA with correlation coefficients of 0.9997, 0.9994, and 0.9999, respectively. The detection limits for LDME, L-DOPA, and DA were 14.6, 98.0, and 9.7 ng mL(-1), respectively. Recoveries were 80.3% for LDME, 93.5% for L-DOPA, and 86.5% for DA. This method was applied to serum samples after intravenous injection of LDME and L-DOPA to rats.
Wang
J
J
Department of Chemistry, East China Normal University, Shanghai, 200062, PR China. yuzhi@online.sh.cn
Zhou
Y
Y
Wang
A F
AF
Zhang
S H
SH
Ning
L
L
He
P G
PG
Fang
Y Z
YZ
D000818:Animals; D001711:Biotransformation; D002021:Buffers; D004563:Electrochemistry / Q000379:methods*; D019075:Electrophoresis, Capillary / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007980:Levodopa / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D002021:Buffers; D007980:Levodopa; C035420:levodopa methyl ester