title: Direct determination of ecgonine methyl ester and cocaine in rat plasma, utilizing on-line sample extraction coupled with rapid chromatography/quadrupole orthogonal acceleration time-of-flight detection.
abstract: Our current experiments assess the applicability of on-line sample extraction with coupled rapid chromatography systems to quadrupole orthogonal acceleration time-of-flight (Q-TOF) detection for the quantitative analysis of cocaine (COC), and ecgonine methyl ester (EME) in rat plasma. Experiments were performed on a Q-TOF instrument, operated in the MS/MS mode. Quantitation was achieved utilizing the most prominent parent-daughter transition and internal standard calibration techniques (COC-d3: IS). The calibration curves produced for EME and COC ranged from 5.0 to 10,000 and 0.5 to 10,000 ng/ml, respectively. Equations of regression line and correlation coefficients for the pseudo-multiple reaction monitoring (MRM) ion abundance ratio and the corresponding calibration concentrations (r2) were as follows: y = 0.0003 + 0.0703x (r2 = 0.9921) for EME and y = 0.0032 + 0.0035x (r2 = 0.9997) for COC. The system repeatability, given as percent coefficient of variation (% CV) of mean peak-area ratios, was assessed using 50 injections of a rat plasma sample from the pharmacokinetic study. The analyses were performed over the course of 5 days, rendering % CVs for EME and COC of 0.73 and 0.58, respectively. This method suggests that on-line sample extraction coupled with fast liquid chromatography/quadrupole orthogonal time-of-flight mass spectrometry may be a viable alternative for quantitative analysis of EME and COC in rat plasma.
authors.affiliation: Drug Metabolism Technology Department, Pfizer Inc., Central Research Division, Groton, CT 06340, USA. patrick_jeanville@groton.pfizer.com
authors.forename: P M
authors.initials: PM
authors.lastname: Jeanville
authors.forename: J H
authors.initials: JH
authors.lastname: Woods
authors.forename: T J
authors.initials: TJ
authors.lastname: Baird
authors.forename: E S
authors.initials: ES
authors.lastname: Estapé
mesh_terms: D000818:Animals; D002091:Butyrylcholinesterase / Q000378:metabolism; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D003042:Cocaine / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D004563:Electrochemistry; D013058:Mass Spectrometry; D009294:Narcotics / Q000097:blood* / Q000493:pharmacokinetics; D051381:Rats; D015203:Reproducibility of Results
chemical_list: D009294:Narcotics; D002091:Butyrylcholinesterase; D003042:Cocaine; C034524:ecgonine methyl ester