Flow Injection Photometric Determination of Zinc and Copper With Zincon Based on the Variation of the Stability of the Complexes With pH

Abstract

A flow injection photometric method for the sequential determination of zinc and copper in mixtures was developed based on the variation of the stability of the chromogenic complexes between the analytes and the reagent zincon with pH. At pH 5.0 only the Cu-zincon complex exists, whereas at pH 9.0 the copper and zinc chelates co-exist. A three-channel manifold was implemented containing two alternating buffer streams (pH 5 and 9) which permit the colored reaction products to be formed sequentially at both pH values, and consequently the mixtures can be resolved. A continuous preconcentration unit (Chelex-100) was used in order to increase the sensitivity of the method, thus allowing the analysis of water samples in which the analytes are present at the ng ml-1 level. On the other hand, preconcentration was not required when the analytes were determined in brass. Under the optimum conditions and using a preconcentration time of 2 min, the detection limits (3 sigma) were found to be 0.35 and 0.80 ng ml-1 for zinc and copper, respectively. The repeatability of the method, expressed as the RSD, was in all instances less than 3.1%. Considering the sequential determination of both species, a sampling rate of 70 h-1 was obtained if preconcentration of the samples was not required.

Purification, Functional Reconstitution, and Characterization of the Saccharomyces cerevisiae Isoprenylcysteine Carboxylmethyltransferase Ste14p

“…These data suggest that the local environment surrounding the metal ion is hydrophobic. Furthermore, the inhibition by Zincon suggests the presence of either copper or zinc in the enzyme but does not conclusively rule out other metals (30,35). We are currently attempting to identify the metal from the purified enzyme using inductively coupled plasma mass spectiometry (ICPMS) and determining the identity of the chelating amino acid ligands.…”

Spectrophotometric Determination of Trace Amount of Copper(II) Ion Based on Complexation with an Anthraquinone Derivative

“…Although numerous organic reagents, such as PAN, 17 zincon, 18 PAR 19 and DDTC 20 have been proposed for the spectrophotometric determination of copper, none of the methods presently available are completely satisfactory. In analytical chemistry, anthraquinone derivatives have been widely used, mainly as strong chelating agents and chromophores.…”

Univariate and Simplex Optimization for the Flow-Injection Spectrophotometric Determination of Copper Using Nitroso-R Salt as a Complexing Agent

“…Although numerous organic reagents, such as PAN, 22 zincon, 23 PAR, 24 and DDTC, 25 have been proposed for the spectrophotometric determination of copper, none of the methods presenting available are completely satisfactory. Disodium 1-nitroso-2-napthol-3,6-disulfonate (Nitroso-R salt) was first introduced in 1921 by Van Klooster for the determination of cobalt 26 and subsequently used by various investigators for the determination of cobalt, 27,28 iron, 29 copper, [30][31][32] and nickel.…”