Determination of Co(II) Ion as a 4-(2-Thiazolylazo)resorcinol or 5-Methyl-4-(2-thiazolylazo)resorcinol Chelate by Reversed-Phase Capillary High-Performance Liquid Chromatography

Abstract

Determination of Co(II) ion as a 4-(2-thiazolylazo)resorcinol(TAR) or 5-methyl-4-(2-thiazolylazo)resorcinol (5MTAR) chelate was accomplished by reversed-phase capillary high-performance liquid chromatography (RP-Capillary-HPLC) using a Vydac C 4 column and MeCN-water mixture as mobile phase. The effect of change in pH and MeCN percentage of the mobile phase on the retention factor, k and peak intensity were evaluated. It was found that 30% MeCN (v/v) of pH 5.60 or 7.20 was adequate as mobile phase when TAR or 5MTAR is used. Detection limit (D.L., S/N=3) in each case was 2.0 × 10 −7 M (11.8 ppb) and 3.0 × 10 −7 M (17.7 ppb). The Co(II) ion in mineral and waste water was determined with the optimum column and mobile phase.

Extraction-Chromogenic System for Cobalt Based on 5-Methyl-4-(2-thiazolylazo) Resorcinol and Benzalkonium Chloride

“…44 This reagent has also been used for the reversed-phase capillary high-performance liquid chromatographic determination of Co II . 45 There are no reports on the liquid-liquid extraction of Co complexes with MTAR, nor on the ternary Co-MTAR complexes with auxiliary reagents.…”

Liquid-Liquid Extraction-Spectrophotometric Investigations of Three Ternary Complexes of Vanadium(V)

“…4 Since many azo dyes were examined in the mentioned works 1−4 and TAO turned out to be less sensitive colorimetric reagent than other of the suggested compounds, 1−7 its analytical potential remained unexploited for 2−3 decades. It was not until the beginning of the new millennium, that some analytical applications of TAO appeared, namely determination of cobalt, 8 cadmium, 9 titanium, 9,10 gold, palladium and lead, 11 copper and nickel, 12 and cadmium and lead. 13 The separation/preconcentration techniques used in these applications were chromatography, 8,9 sorption onto activated carbon, 9,10 coprecipitation, 11 solid phase extraction, 12 and cloud-point extraction.…”