Sensitized phosphorescence as detection method for the enantioseparation of bupropion by capillary electrophoresis

Abstract

A new CE detection method was developed for the chiral drug bupropion (a second-generation antidepressant), based on phosphorescence both in the direct and in the sensitized mode using pulsed laser excitation at 266 nm. Electrokinetic chromatography using 5 mM sulfated-α-CD as chiral selector in 25 mM phosphate buffer at pH 3 allowed the separation of bupropion enantiomers with a high chiral resolution (Rs>3). In the sensitized phosphorescence detection mode, excitation energy is transferred from the analyte to an acceptor (1-bromo-4-napthhalenesulfonic acid or biacetyl) followed by time-resolved phosphorescence detection under deoxygenated buffer conditions. Using 2 × 10(-4) M biacetyl as the acceptor an LOD of 2 × 10(-7) M was obtained for each enantiomer, about 40 times better than in the direct mode. Under these separation conditions, no significantly different phosphorescence lifetimes (measured on-line) were obtained for the two bupropion enantiomers. The suitability of the method was demonstrated with the quantification of bupropion in a pharmaceutical formulation and its determination in a spiked urine sample.

Recent approaches in sensitive enantioseparations by CE

“…A comparison in terms of sensitivity between direct phosphorescence and sensitized phosphorescence modes, which were employed as detection systems for the determination of bupropion enantiomers, is depicted in Fig. 6 60. As it can be observed in this figure, an improvement in the sensitivity of 40‐times was achieved using the sensitized phosphorescence mode.…”

“…Several works published by Gooijer's research group have demonstrated the potential of phosphorescence as detection technique in sensitive chiral analysis. In this works, LED 58 or Nd‐YAG laser 59, 60 was employed as excitation sources using a sensitized phosphorescence mode. As shown in Table 3, different EKC methods coupled to phosphorescence detection were developed for the determination of camphorquinone 58, 59 and bupropion 60 in standards and different real samples.…”

Quenched phosphorescence as alternative detection mode in the chiral separation of methotrexate by electrokinetic chromatography

“…Next to fluorescence detection, which is well established in CE, room temperature phosphorescence (RTP) in liquid deoxygenated solutions was shown to be an attractive luminescence spectroscopic method for detection in CE [19–27]. Apart from direct phosphorescence, where the analyte is excited by light of an appropriate wavelength and phosphoresces itself, several indirect phosphorescence modes can be distinguished.…”

“…In one sensitized mode, the analyte is excited and transfers its excitation energy to a more strongly phosphorescent acceptor added to the background electrolyte (BGE), after which the emission of the latter is observed. That approach was used in a previous paper on the enantioseparation and phosphorescence detection of bupropion [27]. Alternatively, one can excite a donor reagent with excellent absorption properties, which then transfers its electronic energy to the analyte of which the emission is detected [28].…”

Application of ion-association titration for the assay of bupropion hydrochloride in pharmaceuticals

“…graphy (LC) [13][14][15], liquid chromatography mass spectrometry (LC-MS) [16], liquid chromatography--tandem mass spectrometry (LC-MS/MS) [17][18][19], liquid chromatography electrospray ionization-tandem mass spectrometry (LC/ESI/MS/MS) [20], capillary electrophoresis [21] and radioimmunoassay [22]. Several methods have been reported for the determination of BUPH in pharmaceuticals such as non--aqueous titration [23], HPLC [23][24][25][26], gas liquid chromatography (GLC) [27], LC [28], thin-layer chromatography (TLC) [29], capillary electrophoresis [21], polarography [30], potentiometry [31], conductometry [31], UV-spectrophotometry [31,32] and visible spectrophotometry [33,34].…”