Use of complexones in chemical analysis. VI. Colorimetric determination of chromium

Determination of Ethylenediaminetetraacetic Acid as Chromium Complex

“…Plumb et al (7), in their determination of the displacement series of metal complexes of ethylenediaminetetraacetic acid, have investigated the formation and properties of a chromium-ethylenediaminetetraacetic acid complex, a purple substance that is quantitatively measurable (9).…”

“…The present report describes a method for the determination of ethylenediaminetetraacetic acid in urine by the rapid production and spectrophotometric measurement of this stable, reproducible complex. The formation constant of chromium with this chelating agent is sufficiently high to preclude the possibility of interference by any of the urinary constituents (9). Therefore, none of the cations or anions present in normal or pathological urine need be removed, and a simple, rapid and accurate procedure is available for.…”

The Versene complexes

“…(7) Specific applications to redox titration involving otherwise unstable oxidation states (17)(18)(19)(20). (8) Colorimetric procedures: (a) the versene complexes are more intensely colored than the corresponding aquo ions (21)(22)(23)(24), and (b) versene can eliminate interferences by sequestering unwanted ions in the aqueous phase while the desired element is extracted into an organic solvent as another colored complex (25). ( 9) Amperometric titrations at the dropping mercury electrode to the disappearance of the diffusion current of the metal in question (26).…”

Water Analysis

“…The universal complexing action of ethylenediaminetetraacetic acid and its salts as described in the publications of Schwarzenbach and coworkers is extending the use of the complexing agents beyond the field of calcium and magnesium titration, where their place has been firmly established. Pribil and coworkers, in a series of publications (101)(102)(103)(104) are reporting on the use of ethylenediaminetetraacetic acid salts in metallic ion analysis as both complexing agent and colorimetric agent. The problem of complexing the fluoride ion which interferes in several colorimetric determinations made in natural water was attacked by Feigl and Schaeffer (25), who used beryllium nitrate as demasking agent for fluoride.…”