title: On-column complexation capillary electrophoretic separation of Fe2+ and Fe3+ using 2,6-pyridinedicarboxylic acid coupled with large-volume sample stacking.
abstract: On-column complexation of Fe2+ and Fe3+ with 2,6-pyridinedicarboxylic acid (2,6-PDCA) formed anionic complexes, which were then separated by capillary zone electrophoresis with direct UV detection at 214 nm. To achieve reasonable separation selectivity and on-column complexation, the conditions such as pH, the concentration of 2,6-PCDA and the EOF modifiers in the electrolyte were examined. The electrolyte contained 5.0 mM 2,6-PDCA, 0.25 mM tetradecyltrimethlammonium bromide (TTAB) and 5% (v/v) acetonitrile at pH 4.0 was optimised for on-column complexation and the separation of Fe[PCDA]2(2-) and Fe[PCDA]2(-). To enhance the detection sensitivity, large-volume sample stacking (LVSS) was used for the on-line preconcentration of Fe[PCDA]2(2-) and Fe[PCDA]2(-). Under the optimised conditions, satisfactory working ranges (0.5-50 microM), lower detection limits (less than 0.1 microM) and good repeatability of the peak areas (R.S.D.: 5.2-7.8%, n = 5) was achieved using LVSS (300 s). With LVSS, the detection sensitivity was enhanced more than 50-fold compared to conventional hydrodynamic injection. The proposed method was used successfully for the determination of Fe2+ and Fe3+ in water samples.
authors.affiliation: CSIRO Land and Water, Adelaide Laboratory, PMB2, University of South Australia, Glen Osmond SA 5064, Australia. zuliang.chen@unisa.edu.au
authors.forename: ZuLiang
authors.initials: Z
authors.lastname: Chen
authors.forename: Ravendra
authors.initials: R
authors.lastname: Naidu
mesh_terms: D019075:Electrophoresis, Capillary / Q000379:methods*; D005290:Ferric Compounds / Q000302:isolation & purification*; D005296:Ferrous Compounds / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D010848:Picolinic Acids; D011725:Pyridines / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet
chemical_list: D005290:Ferric Compounds; D005296:Ferrous Compounds; D010848:Picolinic Acids; D011725:Pyridines; C004860:dipicolinic acid