Nonaqueous capillary electrophoretic separation and thermo‐optical absorbance detection of five tricyclic antidepressants and metabolism of amitriptyline by Cunninghamella elegans

Abstract

We developed a technique based on nonaqueous capillary electrophoresis and laser-based thermo-optical absorbance detection to assay five antidepressants with similar structures and mass-to-charge ratios. A mixture of methanol and acetonitrile with ammonium acetate was essential to achieve baseline resolution of these compounds. We investigated the effects of ammonium acetate concentration, temperature, applied voltage, and capillary length on separation efficiency. The nonaqueous capillary electrophoresis and laser-based thermo-optical absorbance detection technique was used to study the metabolism of amitriptyline by Cunninghamella elegans. Sample preparation procedures were simplified for fast screening of the parent drug and its metabolites. Reproducible electropherograms were obtained from replicate cultures of C. elegans growing in the presence of amitriptyline.

Detection in capillary electrophoresis

“…The detection of 19 amino acids derivatized with phenylthiohydantoin produced in the Edman degradation reaction for protein sequencing was also accomplished with thermooptical absorption techniques by Chen et al [27]. More recently, Dovichi et al [28] have applied PTR successfully to CE and CEC for the detection of five tricyclic antidepressants.…”

Characterization of pharmaceutical drugs by a modified nonaqueous capillary electrophoresis – mass spectrometry method

“…Optimal resolution for imipramine, amitriptyline, clomipramine and trimipramine was observed at pH 8.7. Previous attempts by other investigators [72] demonstrated the separation of five tricyclic antidepressant drugs employing ammonium acetate buffer (20-40 mM), dissolved in methanol/acetonitrile (75:25 v/v). No pH values were reported, and CE determination under these experimental conditions for desipramine and nortriptyline achieved only a partial resolution.…”

A Review of CE Detection Methodologies

“…31 The detection of 19 amino acids derivatized with phenylthiohydantoin produced in the Edman degradation reaction for protein sequencing was also accomplished with thermooptical absorption techniques by Chen et al 34 More recently, Dovichi and co-workers have applied PTR successfully to CE and CEC for the detection of five tricyclic antidepressants. 35 Others have been involved in using PTR systems for detection in CE. For exam- ple, Bruno et al 36 have also reported the use of thermo-optical absorbance detection for CE using a frequency doubled argon-ion laser as the pump beam.…”

“…Dovichi et al [29][30][31][32][33][34][35] have described thermooptical absorbance systems for several different chromophore/laser combinations. For example, a 4 mW HeCd laser was chosen as the pump source for the analysis of DABSYLderivatized amino acids.…”