Novel, Sensitive Voltammetric Methods for Titanium Determination Using Chromotropic Acid and Azo‐Compounds as Complexing Agents

Abstract

Voltammetric behavior of titanium(IV) complexes with chromotropic acid, its azo-derivatives: 2-(4-sulfophenylazo)-1,8-dihydroxy-3,6-naphthalenedisulfonic acid (SPANDS), chromotrope 2B, sulfonazo III and other azo-compounds: calmagite, tropeoline O and kalces was investigated at a hanging mercury drop electrode. These complexes strongly adsorb onto the electrode, thus can be determined by an adsorptive stripping voltammetry (optimal pH about 6). At pH about 3 reduction current enhancement for Ti-kalces complex was observed in the presence of chlorate ions. It is a rare example of a catalytic process with azo-compound as a complexing agent. Signal for Fe-calmagite complex reduction was also observed. Influence of foreign ions and the optimal conditions for titanium determination are described in detail. Additionally, a connection between obtained results and a structure of titanium complexes is discussed.

VOLTAMMETRIC BEHAVIOURS OF Zn(II) AND Ni(II) COMPLEXES WITH ACID RED 1 AT MERCURY ELECTRODE

“…As a similar form to the binding of Ni(II) ions with some azo-compounds 15,34 , the structure of the complex of Ni(II) with AR 1 was proposed as shown in Scheme 2. …”

“…Among the electrochemical techniques, voltammetry has been widely used to study the interactions between metal ions and ligands [5][6][7][8][9][10][11] . The voltammetric and polarographic studies on the metal complexes of the some azo-dye ligands were done in the literature [12][13][14][15][16][17] . AR 1 (also called azophloxine, see Scheme 1) is an azo dye, used in light and fluorescence microscopy as a real acid counterstain 18 .…”

Sensitive adsorptive stripping voltammetric method for determination of trace concentration of titanium in the presence of chloranilic acid as a complexing agent

“…Another important challenge of the procedure of trace metal ions determination is its insensitivity to the organic matrix which is inevitably present in natural water samples. As it was tested using the Triton X-100 as the representative nonionic surface active agent even very small amounts of organic substances (0.5 ppm) disturb or completely block a voltammetric signal of titanium in AdSV procedures [9,11,13,14]. So in the proposed work special attention was focused on precise examination of the influence of different kinds of surface active substances and humic substances on the titanium voltammetric signal.…”

“…Using adsorptive voltammetry stripping (AdSV) analysis, an extremely useful, sensitive and versatile preconcentration scheme can be achieved by controlled accumulation of metal complexes onto the working electrode [3]. Owing to a widespread popularity of AdSV, several complexing agents have been studied for the adsorptive collection of complexes with titanium, such as mandelic acid [4][5][6][7], oxalate [8], cupferron [9], pyrocatechol violet [10], diphenylguanidine and Beryllon III [11], methylthymol blue, xylenol orange and calcein [12], chromotropic acid and azo-compounds [13]. The vast majority of these procedures were developed using hanging mercury drop electrodes [4,6,7,[9][10][11][12][13] or a mercury film electrode [5], only in one procedure a different kind of electrode was applied, that is a modified carbon paste electrode [8].…”

Application of the Bismuth Film Electrode for Voltammetric Determination of Titanium Using Ti(IV)‐Oxalate‐Chlorate Catalytic System

“…Some of these complexes may induce catalytic reactions, which offer an additional increase in the sensitivity. Catalytic-adsorptive systems such as Ti(IV)-ligand-chlorate, in which one of the following substances may act as the ligand: mandelic acid [22,23], pyrocatechol violet [24], Ti(IV)-methylthymol blue [25], xylenol orange and calcein [25], triphenylmethane dyes [26] and kalces [27], are used in the most sensitive methods of Ti(IV) determination and find application in its trace analysis [8].…”