Determination of traces of molybdenum and tungsten by extraction and polarography of their salicoylhydroxamates

A new and very simple procedure for the differential pulse polarographic determination of ultra trace quantities of tungsten using catalytic hydrogen wave and application to tobacco sample

“…A renewable mercury film silver based electrode was used for the determination of ultra traces of tungsten(VI) using differential pulse catalytic adsorptive cathodic stripping voltammetry with presence of catechol as a ligand and chlorate(V) and a preconcentration of 60 s [11]. Molybdenum and tungsten salicoylhydroxamates have been extracted into methyl isobutyl ketone and then determined using differential pulse polarography [12].…”

“…For the determination of tungsten, mostly spectrophotometric [5][6][7][8], voltammetric [9][10][11] and polarographic [12] methods were used.…”

Ultrasensitive determination of tungsten(VI) on pikomolar level in voltammetric catalytic adsorptive catechol-chlorate(V) system

“…The use of a differential pulse mode for recording polarograms [28][29][30][31] permitted the determination of tungsten down to levels of l0 À11 M [29]. A drawback of these polarographic methods is their low selectivity, a fact which makes it necessary to separate tungsten from the sample matrix by extraction techniques [21,23,26,27,30,31]. In the group of voltammetry the stripping methods such as anodic stripping voltammetry on graphite electrodes with the detection limit of 10 À8 M [32] 10 À7 M [33] and 10 À9 M [34] could be obtain but these methods required a long preconcentration time and characterizes of poor precision.…”

“…Polarographic methods with mercury drop electrodes and catalytic current techniques [21,[22][23][24][25][26][27] give better detection limits down to 10 À9 M [24] and even to 10 À12 M after preliminary preconcentration in an ionexchange column [21]. The use of a differential pulse mode for recording polarograms [28][29][30][31] permitted the determination of tungsten down to levels of l0 À11 M [29]. A drawback of these polarographic methods is their low selectivity, a fact which makes it necessary to separate tungsten from the sample matrix by extraction techniques [21,23,26,27,30,31].…”