Simultaneous determination of cobalt and nickel in sea water by adsorptive cathodic stripping square-wave voltammetry

Abstract

A reliable procedure for the simultaneous determination of ultra-trace levels of cobalt and nickel in sea water is proposed, in which the complexes of cobalt and nickel with dimethylglyoxime are analysed by cathodic stripping square-wave voltammetry based on adsorptive collection at a hanging mercury drop electrode. After comparing differential-pulse cathodic stripping voltammetry with cathodic stripping square-wave voltammetry for the determination of cobalt and nickel, the latter technique was adopted because of its inherently greater sensitivity and faster scan rate. The variation of the resolution between the cobalt and nickel peaks and of the peak currents with ligand concentration, buffer concentration, pH, adsorption time and potential, and of the instrumental parameters such as scan rate, pulse height and frequency was studied. The effect of surfactants and foreign metal ions was also examined. The advantages of the proposed method are rapid determination, high sensitivity and good precision. The detection limits for cobalt and nickel are approximately 8 PM and 0.05 nM, respectively. The applicability of this method to the analysis of sea water was assessed by the determination of cobalt and nickel in Mediterranean sea water samples.

Sono-Cathodic Stripping Voltammetry of Lead at a Polished Boron-Doped Diamond Electrode: Application to the Determination of Lead in River Sediment

“…Often, CSV techniques involve complexation of the metal ions of interest, and the use of a hanging mercury drop electrode (HME). Zhang et al [4] reported the analysis of cobalt and nickel from seawater as dimethylglyoxime (DMG) complexes at an HME, and Zhang and Millero [5] analyzed a range of metal ions, including Pb 2 , as sul®de complexes. Cathodic stripping voltammetry methods for directly analyzing aqueous lead have also been developed previously.…”

Determinação simultânea de cobalto e níquel

“…As curvas analíticas foram lineares para 0,1 ng mL -1 , para os dois metais. A utilização da técnica adsortiva de redissolução com varredura catódica em voltametria de onda quadrada, para a determinação simultânea de Co e Ni em água do mar foi descrita por Zhang et al 37 . O pH das amostras foi controlado, com tampão amônia/trietanolamina (pH=8,0), o complexante utilizado foi DMG.…”

Comparative Study to Evaluate the Feasibility of Sono-Anodic and Sono-Cathodic Stripping Voltammetry for the Determination of Pb in a Cu-Pb Alloy

“…Although some of the CSV techniques for lead detection involve complexation and/or the use of a hanging mercury drop electrodes, 21,22 there are also a significant number of reports of successful CSV analysis of lead at various solid electrode substrates. 3,[23][24][25][26][27][28] Classical "nobel" metal electrodes 25 and glassy carbon electrodes 20 can sometimes be limited in terms of sensitivity by surface oxidation and reduction processes, and the amount of Pb 2+ deposited from solution as lead dioxide is often restricted in these cases due to the proximity of solvent decomposition to the cathodic stripping peak of PbO2.…”