A novel and highly sensitive adsorptive voltammetric procedure for direct determination of In(III) in natural water samples was introduced. The method is based on cathodic adsorptive stripping voltammetry of the In(III)-cupferron complex at a renewable mercury film silver based electrode (Hg(Ag)FE). Experimental conditions were established and included: 0.1 mol L−1 acetate buffer (pH = 5.5), 5 × 10−5 mol L−1 cupferron, accumulation potential 0 V. The calibration graph was linear from 5 × 10−10 mol L−1 to 2 × 10−8 mol L−1 with the correlation coefficient of 0.9993. Limit of detection (LOD) and limit of quantification (LOQ) for preconcentration time of 30 s were 1.5 × 10−10 mol L−1 and 5 × 10−10 mol L−1, respectively. The interference of surface active substances and humic substances on the indium voltammetric signal was precisely examined, and effectively minimalized. The application of the procedure to the analysis of natural water samples was validated by the determination of indium in certificate reference materials SPS-WW1 Wastewater and SPS-SW1 Surface Water, river water, rain water and tap water.

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1IntroductionOver the last few decades,g alliumc ompounds have gained importance in the fields of electronics and medicine.I nm edicine severalg allium salts are useda sb oth pharmaceuticals and radiopharmaceuticals.I nc linical medicine,r adioactive galliuma nd stable gallium nitrate are used as diagnostic and therapeutic agents in cancer and disorders of calcium and bone metabolism [1,2].I n electronics,t he most commona pplications for gallium include advanced semiconductors for microwave transceivers,D VDs,l aser diodes in compact discs and other electronic devices.I ni ndustry occupational exposure to gallium may cause healthp roblems,a nd semiconductorp roductionw astesm ay result in environmentalp roblems [3]. Thel evel of galliumi nt he environment around industrial area is beginning to rise,d ue to variousu ses of gallium and gallium compounds.T hati sw hy the determination of gallium traces in environmental samples was studied [4].Electrochemical techniques seem to be suitable for direct metali on determination because they offer highly sensitive detection with low-cost portable instrumentation and are simple,r eliable and easy to use.I nt race analysis of gallium, anodic stripping voltammetry (ASV) and adsorptivec athodics trippingv oltammetry (AdCSV) are mainly used. Thea nodic stripping determinationo fg allium is based on the formation of its amalgama nd is carried out mainly on different mercury electrodes [5][6][7][8][9][10], such as hangingm ercury drop electrodes (HMDE) [5][6][7][8], stirring mercury electrode [9],r enewable mercury film silver basede lectrode (Hg(Ag)FE) [10],m ercury film electrode [11],H gBi thinf ilm electrode [12] and recently on bismuth film electrodes [12,13].A nodic stripping voltammetry is ap otentially attractive approach for trace quantification of gallium, but its main drawbackc onsists in the formationo fi ntermetallic compoundsb etween gallium and zinc, copper,o rn ickel [4].T herefore as an alternative stripping approach for trace quantitation of gallium the adsorptive cathodics trippingv oltammetry (AdCSV) can been applied.I nt his case also mercury electrodes are mainly used,H MDE [14][15][16][17] or Hg(Ag)FE [18,19].I nl iterature data we found only one adsorptive voltammetric procedure for galliumd eterminationu sing mercuryf ree electrode,t hat is carbon paste electrode [20].T he major drawback of mercury electrodesi st heir high toxicity,s oa ttempts to replace them with less toxic ones is ani mportant challenge.In the last few years lead film electrodes were introduced for stripping analysis and they have been applied until today for the determination of selected metal ions, Co(II), Ni(II), U(VI),P t(IV) [21][22][23][24][25][26].I np aper [27] the microscopic and electrochemicalc haracterizationo ft he lead film electrode applied in adsorptive stripping analysis was precisely described.In the present study,w eu sed al ead film electrode (PbFE) formed in situ and appliedi tt og allium determination by AdCSV.T he application of the in situ formed lead film ele...

A sensitive and selective method for the determination of trace concentration of indium in natural water samples using adsorptive stripping voltammetry at an in situ plated bismuth film electrode was described.