Use of cyclodextrins in capillary electrophoresis: Resolution of tramadol enantiomers

Abstract

Capillary zone electrophoresis was successfully applied to the enantiomeric resolution of racemic tramadol. Both uncoated and polyacrylamide-coated capillaries were tested for method optimization using either negatively charged or native cyclodextrins (CD) added to the background electrolyte (BGE). The resolution was strongly influenced by the CD type and concentration as well as by the pH and the concentration of the BGE. Among the CDs tested, carboxymethylated-beta-cyclodextrin allowed the baseline separation of tramadol enantiomers. After the method was optimized, it was validated in a coated capillary for enantiomeric analysis of tramadol enantiomers in pharmaceutical formulation, including specificity and elution order, linearity, accuracy and precision, determination of limit of detection (LOD) and quantification (LOQ), enantiomeric purity linearity, freedom from interference, and stability of sample solutions. Precision at the target concentration was less than 2%, with an accuracy higher than 99%. Furthermore, the method was able to detect 0.3% and to quantify 1% of the minor enantiomer in the presence of the major one at the target value.

Experimental designs to investigate capillary electrophoresis-electrospray ionization-mass spectrometry enantioseparation with the partial-filling technique

“…SBE is negatively charged at any pH commonly used in CE, due to four sulfonic groups bond at the CD rim. As previously described, CMB can be used both in an ionized or a neutral form depending on the buffer pH [42]. At the selected pH value of 4.0, carboxylic functions are partially deprotonated.…”

“…For each CD, the following responses were measured: the enantiomeric resolution of Mtd (R s ), the migration time (t) and efficiency (N) for both enantiomers, and the apparent selectivity (a*) which gives important information about the enantiodiscrimination, as described elsewhere [42]. For the sake of clarity, resolution of Mtd enantiomers (R s ), migration time of the second enantiomer (t 2 ) and apparent selectivity (a*) are reported in Table 2.…”

Separation of reboxetine enantiomers by means of capillary electrophoresis

“…Among the chiral recognizing agents, CDs are the compounds employed most in CE because (i) they are generally transparent at the wavelengths employed for the analysis, (ii) they are commercially available, (iii) they can be modified (charged or uncharged groups), (iv) they can be dissolved in the BGE used in CE, and finally (v) a wide number of compounds of pharmaceutical interest interact with them [38][39][40][41].…”

Simultaneous determination of ethamsylate, tramadol and lidocaine in human urine by capillary electrophoresis with electrochemiluminescence detection

“…The high efficiency and resolution potential, relatively short analytical time, low instrumental costs and small sample volume make CE an alternative to HPLC for the determination of drugs in biological fluids [30,31] and the separation of metabolite mixtures [32,33]. A series of methods based on CE with ECL detection of tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy) 3 21 ), wherein a chemiluminescence reaction is initiated from reagents in the vicinity of the working electrode surface when potential is applied, have been developed for tertiary amines and their derivatives [22,[27][28][29][34][35][36][37].…”