Improving sensitivity in simultaneous determination of copper carboxylates by nonaqueous capillary electrophoresis

• Published in: Journal of Chromatography A Vol. 1110; no. 1; pp. 261 - 267
• Main Authors: Laamanen, Pirkko-Leena, Blanco, Eva, Cela, Rafael, Matilainen, Rose
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31.03.2006; Elsevier
• Subjects: Analysis methods; Analytical chemistry; Applied sciences; Bromides - chemistry; Buffers; Calibration; Carboxylic Acids - analysis; Carboxylic Acids - chemistry; Chelating agents; Chelating Agents - analysis; Chemistry; Chromatographic methods and physical methods associated with chromatography; Copper - analysis; Copper - chemistry; Copper carboxylate complexes; Edetic Acid - analogs & derivatives; Edetic Acid - analysis; Electrolytes; Electrophoresis, Capillary - methods; Exact sciences and technology; Formamides - chemistry; Hydrogen-Ion Concentration; Large-volume sample stacking; N-Methylformamide; Natural water pollution; Nonaqueous capillary electrophoresis; Organometallic Compounds - analysis; Other chromatographic methods; Pollution; Potassium Compounds - chemistry; Sensitivity and Specificity; Water Pollutants, Chemical - analysis; Water treatment and pollution; Large-volume sample stacking; Nonaqueous capillary electrophoresis; Chelating agents; Copper carboxylate complexes; N-Methylformamide; Trace analysis; Chemical analysis; Capillary electrophoresis; Organic ligand; Transition metal Complexes; Copper Complexes; Chemical enrichment; Sensitivity; Ultraviolet detector; Aminoacid; Surface water; Simultaneous measurement; Carboxylate; Chelating agent; Water pollution; Non aqueous solvent; Quantitative analysis
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2006.01.091

A new method of nonaqueous capillary electrophoresis (NACE) with UV spectrophotometric detection was developed and optimized for the simultaneous determination of seven carboxylates (trans-1,2-diaminocyclohexane- N, N, N′, N′-tetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediamine- N, N′, N′-triacetic acid (HEDTA), nitrilotriacetic acid (NTA), 1,3-diaminopropane- N, N, N′, N′-tetraacetic acid (PDTA) and triethylenetetraaminehexaacetic acid (TTHA)) as copper complexes. The method development was carried out by using a fused silica capillary. Background electrolyte (BGE) was optimized and the best separation achieved by using 30 mmol L −1 potassium bromide in N-methylformamide (NMF) at apparent pH (pH app) 10.2. A voltage of +30 kV and direct UV detection at 280 nm were used in all measurements. Large-volume sample stacking using the electroosmotic flow pump (LVSEP) was tested in addition to basic capillary electrophoresis (CE) and observed to improve the separation of the analyte zones in the capillary. All the peaks in the electropherograms were properly separated, the calibration plots gave excellent correlation coefficients ( R 2 ≥ 0.994) and all seven copper carboxylate complexes were detected in less than 20 min using both the basic measurements and the large-volume sample stacking method. The new NACE method was tested with lake water and proved to be reliable.