Coulometric Titration of Ethylenediaminetetraacetate (EDTA) with Spectrophotometric Endpoint Detection: An Experiment for the Instrumental Analysis Laboratory

Abstract

Ethylenediaminetetraacetate (EDTA) is commonly used as an anticoagulant in blood-collection procedures. In this experiment for the instrumental analysis laboratory, students determine the quantity of EDTA in commercial collection tubes by coulometric titration with electrolytically generated Cu2+. The endpoint is detected spectrophotometrically using a UV−vis spectrophotometer equipped with a fiber optic probe. Students gain experience with two instrumental methods and learn about a practical application of complexation chemistry.

Implementation of Coulometric Titration System at Constant Current for Certification of Primary Reference Materials

“…The reaction mechanism of EDTA-Na 2 titration was similar to that of previous studies [7], with the difference being that copper cations were produced by ionic complex [Cu(EDTA)] 2-. The reaction was followed by spectrophotometric measurements and the endpoint was detected when ionic specie [Cu(H 2 O) 6 ] 2+ appeared after that ionic specie [H 2 (EDTA)] 2-was completely consumed.…”

“…Systems have been bubbling using argon (99,999% purity UHP). [7] An aqueous solution of EDTA (0,0958 mol·kg -1 ) was prepared for diluting EDTA-Na 2 (Merck -99% purity) in ultrapure water. Approximately 1 g of this dissolution, weighed in microbalance, was titrated with Cu 2+ electrochemically generated at 30 mA from a Cuelectrode.…”

Reversible “Off–On” Fluorescence of Zn2+-Passivated Carbon Dots: Mechanism and Potential for the Detection of EDTA and Zn2+

“…24 Therefore, it is very meaningful to determine the existence of trace amounts of EDTA in solution. Unfortunately, the conventional analytical techniques for the detection of EDTA are including titrimetry, 25 high-performance liquid chromatography (HPLC), 26 atomic absorption spectrometry, 27 ion chromatography, 28 and so on, which are not convenient because of the unsatisfactory limit of detection (LOD), the complicated sample pretreatment, and the requirements of expensive equipment. With the advantages of easy operation, high sensitivity, and selectivity, the fluorescent sensor is a good alternative.…”

Complexometric titrations: new reagents and concepts to overcome old limitations

“…[8][9][10][11] Powerful instrumental analysis methods such as potentiometry, conductometry, thermometry, coulometry and chronopotentiometry were also developed to provide improved choices for quantitative analyses. [12][13][14][15][16][17][18][19] Although EDTA has always been the most widely recognized chelator in complexometric titration, good chelators and indicators as well as new concepts have been continuously emerging. In addition, various titration protocols have been developed.…”