TY - JOUR
T1 - 1-Butyl-3-methylimidazolium-based ionic liquids and an anionic surfactant
T2 - Excellent background electrolyte modifiers for the analysis of benzodiazepines through capillary electrophoresis
AU - Su, Hsiu Li
AU - Kao, Wan Chun
AU - Lin, Kuan Wen
AU - Lee, Cheng yu
AU - Hsieh, You-Zung
PY - 2010/1/1
Y1 - 2010/1/1
N2 - In this study, we found that adding 1-butyl-3-methylimidazolium-based ionic liquids (ILs) and sodium dodecyl sulfate (SDS) as modifiers in the background electrolyte (BGE) for capillary elec-trophoresis enhanced the separation of benzodiazepines. In particular, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([BMIM][NTf2]) was the best IL additive for the separation system because its anionic moiety interacted favorably with the benzodiazepines. We added SDS because of its known effect on the separation of hydrophobic analytes. We optimized the separation conditions in terms of the concentrations of the IL, SDS, and organic solvent, the pH, and the BGE's ionic strength. The optimal BGE, containing 170 mM [BMIM][NTf2] and 10 mM SDS, provided baseline separation, high efficiency, and satisfactory peak shapes for the benzodiazepines. The separation mechanism was based on heteroassociation between the anionic moiety of the IL and the benzodiazepines, with SDS improving the resolution of the separation. The limits of detection for the seven analytes ranged from 2.74 to 4.42 μg/mL. We subjected a urine sample to off-line solid phase extraction (SPE) prior to the analysis of its benzodiazepine content. Our experimental results reveal that the combination of [BMIM][NTf2] and SDS provides adequate separation efficiency for its application to CE analyses of benzodiazepines after SPE concentration.
AB - In this study, we found that adding 1-butyl-3-methylimidazolium-based ionic liquids (ILs) and sodium dodecyl sulfate (SDS) as modifiers in the background electrolyte (BGE) for capillary elec-trophoresis enhanced the separation of benzodiazepines. In particular, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([BMIM][NTf2]) was the best IL additive for the separation system because its anionic moiety interacted favorably with the benzodiazepines. We added SDS because of its known effect on the separation of hydrophobic analytes. We optimized the separation conditions in terms of the concentrations of the IL, SDS, and organic solvent, the pH, and the BGE's ionic strength. The optimal BGE, containing 170 mM [BMIM][NTf2] and 10 mM SDS, provided baseline separation, high efficiency, and satisfactory peak shapes for the benzodiazepines. The separation mechanism was based on heteroassociation between the anionic moiety of the IL and the benzodiazepines, with SDS improving the resolution of the separation. The limits of detection for the seven analytes ranged from 2.74 to 4.42 μg/mL. We subjected a urine sample to off-line solid phase extraction (SPE) prior to the analysis of its benzodiazepine content. Our experimental results reveal that the combination of [BMIM][NTf2] and SDS provides adequate separation efficiency for its application to CE analyses of benzodiazepines after SPE concentration.
KW - 1-Butyl-3-methylimidazolium
KW - Benzodiazepine
KW - Bis(trifluoromethanesulfonyl)imide
KW - Capillary electrophoresis
KW - Ionic liquids
UR - http://www.scopus.com/inward/record.url?scp=77953689702&partnerID=8YFLogxK
U2 - 10.1016/j.chroma.2010.02.056
DO - 10.1016/j.chroma.2010.02.056
M3 - Article
C2 - 20299026
AN - SCOPUS:77953689702
VL - 1217
SP - 2973
EP - 2979
JO - Journal of Chromatography A
JF - Journal of Chromatography A
SN - 0021-9673
IS - 17
ER -