Chiral analysis of baclofen by α-cyclodextrin-modified capillary electrophoresis and laser-induced fluorescence detection

Abstract

An enantioselective method for baclofen (4-amino-3-p-chlorophenylbutyric acid) based on capillary electrophoresis (CE) separation and laser-induced fluorescence (LIF) detection has been developed. Naphthalene-2,3-dicarboxaldehyde (NDA) was used for precolumn derivatization of the nonfluorescent drug. alpha-Cyclodextrin (alpha-CD) was included in the buffer as a chiral selector for the separation of NDA-labeled S-(+)- and R-(-)-baclofen. Optimal resolution and detection were obtained with an electrophoretic buffer of 50 mM sodium borate (pH 9.5) containing 7 mM alpha-CD and a He-Cd laser (lambda ex = 442 nm, lambda em = 500 nm). Combined with a simple cleanup procedure, this method can be applied to the analysis of baclofen enantiomers in human plasma. The relative standard deviation (RSD) values on peak areas of a plasma sample containing 1.0 microM racemic baclofen were 6.4 and 4.9% (n = 8) for the S-(+)- and R-(-)-enantiomer, respectively. The RSD value on migration times of both enantiomers was 0.5% (n = 8). Calibration graphs for S-(+)- and R-(-)-baclofen in plasma showed a good linearity (r > or = 0.999) in the concentration range of 0.1-2.0 microM. The limit of detection of baclofen in plasma was about 10 ng/mL.

Stereoselective determination of drugs and metabolites in body fluids, tissues and microsomal preparations by capillary electrophoresis (2000–2010)

“…[78,84,94,100,106]. Other detection principles employed include laser induced fluorescence (LIF) [54,62,77,88,90,100,122,124], lamp based fluorescence (F) [97,142], electrospray ionization mass spectrometry (ESI-MS) [50,51,59,66,68,73,127,[145][146][147][148], and electrochemiluminescence (ECL) [60]. These four detection modes also provide increased selectivity which is useful for identification of solutes.…”

“…Furthermore, on-column preconcentration can also be attained by electrokinetic injection (for assay examples see Refs. [51,54,57,73,75,89,103,108,116,145]) and stacking procedures [49,71,75,79,87,100,108,116]. Electrophoretic mass transport is highly regulated, this allowing charged solutes to be concentrated (stacked) across an electrolyte discontinuity, including that produced initially between sample and running buffer.…”

Enantioseparation of baclofen with highly sulfated β‐cyclodextrin by capillary electrophoresis with laser‐induced fluorescence detection

“…The mean recoveries of R-( -)-and S(+)-baclofen in plasma sample spiked with 1.0 lM baclofen were 98 and 97% (n = 4), respectively. In comparison with published data [36] using native a-CD, this work investigated the effect of HS-CD chiral selectors on the enantioseparation of baclofen and the method was applied to plasma samples. Results showed good enantiomer resolution and short analysis time without any disturbance from endogenous plasma components.…”

“…As reported in the literature, there are only few papers dedicated to the chiral separation of baclofen by CE with derivatized CDs [33] and crown ethers [34,35] in acidic media with UV detection. However, to our knowledge, there is only one study presenting LIF detection [36] and a-CD as chiral selector. In comparison to UV detection, LIF provides lower detection limits and better selectivity, thus increasing the applicability of CE to biological and clinical analyses.…”

Recent developments in chiral capillary electrophoresis and applications of this technique to pharmaceutical and biomedical analysis

“…, have been successfully employed for enantioseparation of basic [53, 56, 63± 71] and acidic enantiomers [24,72], derivatized amino acids [36,41,73], dipeptides [74,75,59,76], carnitine [77], baclofen [78], racemic dihydropyridines [79], atropine [53], thiamphenicol-related compounds [80], medicarpine and vestitone [81], lobeline analogous [66], and galanthamine and related drugs [65]. Enantiomeric separation of drugs using neutral CDs as chiral selectors has been discussed by Koppenhoefer and co-workers [54].…”