Determination of ammonium and metal ions by capillary electrophoresis-potential gradient detection using ionic liquid as background electrolyte and covalent coating reagent.
A capillary zone electrophoresis (CZE)-potential gradient detection (PGD) method coupled with field-amplified sample injection was developed to determine alkali metal, alkaline-earth metal, nickel, lead and ammonium ions. The capillary surface was coated with dialkylimidazolium-based ionic liquid and thus the electroosmotic flow (EOF) of the capillary was reversed. The buffer composed of 7.5 mM lactic acid, 0.6 mM 18-crown-6, 12 mM alpha-cyclodextrin (alpha-CD); it was adjusted to pH 4.0 by 1-hexyl-3-methylimidazolium hydroxide. The 11 cations were baseline separated within 14 min with 5.1-18.9 x 10(4) plates (for 40-cm-long capillary) in separation efficiency, and the detection limits were in the range of 0.27-7.3 ng/ml. The method showed good reproducibility in terms of migration time with RSD < or = 0.90% for run-to-run and < or = 1.65 for day-to-day assessment.
Qin
Weidong
W
Department of Chemistry, National University of Singapore, Singapore 119260, Singapore.
Li
Sam Fong Yau
SF
D002021:Buffers; D004573:Electrolytes / Q000737:chemistry*; D019075:Electrophoresis, Capillary / Q000379:methods*; D007093:Imidazoles / Q000737:chemistry; D007202:Indicators and Reagents; D007477:Ions / Q000032:analysis*; D019344:Lactic Acid / Q000737:chemistry; D008670:Metals / Q000032:analysis*; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D015203:Reproducibility of Results; D047391:alpha-Cyclodextrins / Q000737:chemistry
D002021:Buffers; D004573:Electrolytes; D007093:Imidazoles; D007202:Indicators and Reagents; D007477:Ions; D008670:Metals; D000644:Quaternary Ammonium Compounds; D047391:alpha-Cyclodextrins; D019344:Lactic Acid; C032613:alpha-cyclodextrin