title: Field-enhanced sample injection-micelle to solvent stacking in nonaqueous capillary electrophoresis.
abstract: The low conductivity of separation electrolytes employed in nonaqueous capillary electrophoresis (NACE) limits the use of on-line sample concentration or stacking by field enhancement. Herein, micelle-to-solvent stacking (MSS) was performed by the simple injection of a micellar solution plug prior to electrokinetic injection of sample prepared under field-enhanced stacking conditions (known as field-enhanced sample injection, FESI). The proposed approach allowed a 214-625-fold improvement in peak signals for targeted anticancer drugs (e.g., tamoxifen) and its major metabolites in NACE using 100% methanol-based separation electrolyte that comprised of 7.5mM deoxycholic acid sodium salt, 15mM acetic acid and 1mM 18-crown-6. These improvements yielded tamoxifen and its metabolites with 2-5 times better stacking efficiency as compared to those obtained without micellar solution injection or FESI only. This is comparable to the results typically achieved when FESI is combined with isotachophoresis (electrokinetic supercharging). The FESI-MSS-NACE was tested for the measuring levels of target drugs in plasma. The analytical figures of merit are also reported.
authors: Centre for Sustainable Nanomaterials, Ibnu Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia, UTM, Johor Bahru, Johor 81310, Malaysia; Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, UTM, Johor Bahru, Johor 81310, Malaysia.
authors: Lee Yien
authors: LY
authors: Thang
authors: Centre for Sustainable Nanomaterials, Ibnu Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia, UTM, Johor Bahru, Johor 81310, Malaysia; Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, UTM, Johor Bahru, Johor 81310, Malaysia. Electronic address: hhsee@ibnusina.utm.my.
authors: Hong Heng
authors: HH
authors: See
authors: Centre for Sustainable Nanomaterials, Ibnu Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia, UTM, Johor Bahru, Johor 81310, Malaysia; Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, UTM, Johor Bahru, Johor 81310, Malaysia; Australian Centre for Research on Separation Science, School of Physical Sciences - Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia; Department of Chemistry, Ateneo de Manila University, Katipunan Ave., Loyola Heights, Quezon City 1108, Philippines. Electronic address: jquirino@utas.edu.au.
authors: Joselito P
authors: JP
authors: Quirino
keywords: Field enhanced sample injection; Micelle to solvent stacking; Nonaqueous capillary electrophoresis; Plasma; Tamoxifen