Large-volume sample stacking for analysis of ethylenediaminetetraacetic acid by capillary electrophoresis

Abstract

A simple, quick, and sensitive capillary electrophoretic technique-large volume stacking using the electroosmotic flow (EOF) pump (LVSEP) - has been developed for determining ethylenediaminetetraacetic acid (EDTA) in drinking water for the first time. It is based on a precapillary complexation of EDTA with Fe(III) ions, followed by large-volume sample stacking and direct UV detection at 258 nm. The curve of peak response versus concentration was linear from 5.0 to 600.0 microg/L, and 0.7 to 30.0 mg/L. The regression coefficients were 0.9988 and 0.9990, respectively. The detection limit of the current technique for EDTA analysis was 0.2 microg/L with an additional 10-fold preconcentration procedure, based on the signal-to-noise ratio of 3. As opposed to the classical capillary zone electrophoresis (CE) method, the detection limit was improved about 1000-fold by using this LVSEP method. To the best of our knowledge, it represents the highest sensitivity for EDTA analysis via CE. Several drinking water samples were tested by this novel method with satisfactory results.

On-line Sample Preconcentration by Large-volume Sample Stacking with an Electroosmotic Flow Pump (LVSEP) in Microscale Electrophoresis

“…Zhu et al used hydroxyethylcellulose (HEC) as a BGS modifier to suppress the EOF under an acidic condition (pH 4.1) for determining ethylenediaminetetraacetic acid (EDTA) in drinking water by LVSEP-CZE. 39 Due to the cooperative EOF-reducing ability of HEC and acidic BGS, the detection limit of EDTA was improved 1000-fold in the LVSEP method. Kuo et al reported a similar approach using the BGS containing PEO for the determination of methotrexate and its metabolites in human plasma, achieving a SEF of around 100.…”

Luminescence methods for study and determination of pollutants in the environment

“…In order to lower the metal LOD values, various on-capillary pre-concentration techniques were developed, such as sweeping [213], field amplifying stacking [214,215] and transient isotachophoresis [216]. In addition, fluorescence appeared to be well suited to the sensitive detection of complexes formed between trace metal ions and fluorescent chelating reagents, such as 8-hydroxyquinoline-5-sulphonic acid [212], lumogallion [212,217], and fluorescein [218].…”

Analysis of phenolic acids by non-aqueous capillary electrophoresis after electrokinetic supercharging

“…Most of the on-line preconcentration methods in capillary electrophoresis (CE) are based on changes in analyte migration due to conductivity difference, buffer pH difference or the association between the analytes and the surfactants, and the combination of these approaches. Thus methods such as field-amplified sample stacking (FASS) [5][6][7], field-amplified sample injection (FASI) [8], large-volume stacking using the EOF pump (LVSEP) [9][10][11][12][13][14][15][16], fieldamplified sample injection with matrix removal via an EOF pump (FAEP) [17,18], dynamic pH junction (DypH) [19][20][21], transient isotachophoresis (tITP) [22,23], pseudo-transient isotachophoresis (Pseudo-tITP) [24][25][26][27][28], sweeping [29][30][31][32], micelle collapse (MC) [33,34] and various combinations including electrokinetic surpercharging (EKS) [35][36][37][38][39][40][41], selective exhaustive injection [42] and selective exhaustive injection-sweeping (SEI-sweeping) [43][44][45], dynamic pH junction-sweeping [46], and large-volume stacking using the EOF pu...…”