Simultaneous determination of titanium and molybdenum in natural waters by catalytic cathodic stripping voltammetry

Catalytic Adsorptive Stripping Voltammetry of Molybdenum: Redox Kinetic Measurements

“…Figure 2A shows a significant catalytic effect of chlorates on the net SW response of the Mo-mandelic acid system that is in accord with the literature data [5,6,9]. Chlorate at concentration of 4 Â 10 À2 mol dm À3 enlarges the net peak current for more than one order of magnitude (compare curves 1 and 7 in Fig.…”

“…A typical adsorptive stripping SW voltammetric response of Mo-mandelic acid system is presented in Figure 1. The electrode reaction involves a one-electron reduction of the Mo(VI) to Mo(V)-mandelic acid complex [6]. The voltammetric behavior of the system indicates that both Mo(VI) and Mo(V) mandelic acid complexes are strongly adsorbed on the mercury electrode surface.…”

“…The term "catalytic" reaction refers to a homogeneous redox reaction in which the reduced form of the molybdenum complex, which is electrochemically created at the electrode surface, is reoxidized back to the initial oxidized form, thus yielding an increase of the reduction current. For these purposes, diverse oxidative agents has been used such as: chlorate in the case of molybdenum complexes with mandelic acid [5,6], oxine [7], 3-methoxy-4 hydroxymandelic acid [8], and methyl thymol blue [9], bromate for molybdenum complexes with 4-(2-pyridylazo)-resorcinol [10], dihydroxynaphthalene [11], and nitrate for molybdenum complexes with 2-(2'-thiazolylazo)-p-cresol [12], 2-(2'-benzothiazolylazo)-p-cresol [13] and oxine [14].…”

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

“…It was a disadvantage of these methods, as great improvement in the sensitivity of titanium determination can be obtained by coupling the catalytic effect of chlorate ions with AdSV determination. This phenomenon was first described by Koryta and Tengyl [17] for oxalate and was followed by other examples of the similar systems: with mandelic acid [18,19], pyrocatechol violet [13] or triphenylmethane dyes [20]. In the previous article the authors have described catalytic systems with triphenylmethyl compounds for titanium determination in the presence of chlorate ions [21].…”

Determination and validation method of molybdenum by adsorptive catalytic stripping voltammetry at lead film electrode

“…The complexing agents are generally used for voltammetric determination of molybdenum to form stable Mo(VI)-organic ligand complexes and all methods are based on adsorption controlled electrode reaction. These ligands are oxine [5][6][7], methyl thymol blue [8,9], chloranilic acid [10][11][12][13][14], ɑ-benzoin oxime [15][16][17][18], cupferron [19,20], dihydroxynaphtalene [21], p-cresol derivative [22], 1,10-phenanthroline [23], methyl orange [24], 8-hydroxyquinoline [25], pyrogallol red [26,27], mandelic acid [28], cetyltrimethylammonium bromide (CTAB) [29], tiron [30], morin [31], alizarin violet [32], alizarin red s [4,33,34] and azo compounds [35]. These methods were summarized in Table 1.…”