Preparation of Hydroxypropyl‐β‐cyclodextrin Cross‐linked Multi‐walled Carbon Nanotubes and Their Application in Enantioseparation of Clenbuterol

Abstract

A method of cross-linking multi-walled carbon nanotubes by a nucleophilic substitution of brominated multi-walled carbon nanotubes using hydroxypropyl-β-cyclodextrin anions was studied. The modified multi-walled carbon nanotube samples were characterized using thermogravimetric analysis, energy-dispersive X-ray spectroscopy, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and Fourier transform infrared spectroscopy. The hydroxypropyl-β-cyclodextrin modified multi-walled carbon nanotubes were used as a chiral stationary phase additive for thin-layer chromatography to separate clenbuterol enantiomers, and the chiral separation factor was increased.

Application of Carbon Nanotubes in Chiral and Achiral Separations of Pharmaceuticals, Biologics and Chemicals

“…MWCNTs were brominated [79], and then MWCNT-Br was added to HP-β-CD to initiate a nucleophilic reaction. MWCNT-HP-β-CD was then formed, characterized by FT-IR and investigated as stationary phase in TLC for chiral separation of clenbuterol ( Figure 3) [59]. [59] The functionalization of MWCNTs with HP-β-CD enhances the enantioseparation of metoprolol enantiomers as compared with HP-β-CD without MWCNTs [80].…”

“…MWCNT-HP-β-CD was then formed, characterized by FT-IR and investigated as stationary phase in TLC for chiral separation of clenbuterol ( Figure 3) [59]. [59] The functionalization of MWCNTs with HP-β-CD enhances the enantioseparation of metoprolol enantiomers as compared with HP-β-CD without MWCNTs [80]. The application of MWCNT-HP-β-CD for TLC system was found to significantly increase the resolution factor (RF = 5.27) of the racemic compound clenbuterol as compared to HP-β-CD only (RF = 3.35) (Figure 4) [59].…”

“…[59] The functionalization of MWCNTs with HP-β-CD enhances the enantioseparation of metoprolol enantiomers as compared with HP-β-CD without MWCNTs [80]. The application of MWCNT-HP-β-CD for TLC system was found to significantly increase the resolution factor (RF = 5.27) of the racemic compound clenbuterol as compared to HP-β-CD only (RF = 3.35) (Figure 4) [59]. Although good separation was achieved using HP-β-CD alone, the addition of MWCNT enhanced the enantioseparation dramatically [59].…”

“…The application of MWCNT-HP-β-CD for TLC system was found to significantly increase the resolution factor (RF = 5.27) of the racemic compound clenbuterol as compared to HP-β-CD only (RF = 3.35) (Figure 4) [59]. Although good separation was achieved using HP-β-CD alone, the addition of MWCNT enhanced the enantioseparation dramatically [59]. The resolution factor of clenbuterol in the presence of MWCNT-HP-β-CD has been improved by 57% compared to the use of HP-β-CD only [59].…”

“…Since the use of unmodified MWCNTs or MWCNTs modified with HP-β-CD in TLC showed significant enantioseparation of compounds such as clenbuterol and ofloxacin, CNTs might be useful for the separation of other pharmaceuticals such as fluoroquinolone antibiotics and clenbuterol analogues including β2-adrenoreceptor agonists. [59] Resolution of clenbuterol by using (A) MWCNTs-HP-β-CD in TLC (B) HP-β-CD without MWCNTs in TLC. This was done at room temerature and with 10 mL of acetonitrile/t-butanol (V:V=1:1) as a mobile phase.…”