Direct determination of dissolved cobalt and nickel in seawater by differential pulse cathodic stripping voltametry preceded by adsorptive collection of cyclohexane-1,2-dione dioxime complexes

Journal Article · Mon Feb 01 04:00:00 EST 1988 · Anal. Chem.; (United States)

DOI:https://doi.org/10.1021/ac00154a011· OSTI ID:5372429

Donat, J R; Bruland, K W

A highly sensitive voltametric technique was developed for the direct determination of cobalt and nickel in seawater at picomolar and nanomolar concentrations, respectively. Cyclohexane-1,2-dione dioxime (nioxime) complexes of Co(II) and Ni(II) were concentrated from 10 mL of sample onto a hanging mercury drop electrode by controlled adsorption and the current resulting from reduction of Co(II) and Ni(II) was measured by differential pulse cathodic stripping voltametry. Detailed experiments were conducted to determine the optimal ligand type and concentration, buffer type and concentration, pH, and adsorption potential. Maximum sensitivity was obtained by using a nioxime concentration of 1 x 10/sup -4/ m, a HEPES buffer concentration of 0.03 m, a solution pH of 7.6, and an adsorption potential of -0.6 V. Replicate analyses of seawater reference materials yielded excellent agreement with certified values. Analytical precision for Co and Ni at coastal and open ocean concentrations was approximately +/-5% relative standard deviation. Detection limits for Co and Ni depend upon reagent blanks and are 6 pM and 0.45 nM, respectively, for 15-min adsorption periods.

• Research Organization: Univ. of California, Santa Cruz
• OSTI ID: 5372429
• Journal Information: Anal. Chem.; (United States), Journal Name: Anal. Chem.; (United States) Vol. 60:3; ISSN ANCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102* -- Chemical & Spectral Procedures
400105 -- Separation Procedures
520200 -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ADSORPTION
CATHODES
CHEMICAL ANALYSIS
COBALT
DATA
ELECTRODES
ELEMENTS
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
INFORMATION
LIGANDS
METALS
NICKEL
NUMERICAL DATA
OXYGEN COMPOUNDS
PH VALUE
PULSE TECHNIQUES
QUANTITATIVE CHEMICAL ANALYSIS
QUANTITY RATIO
SEAWATER
SORPTION
TRACE AMOUNTS
TRANSITION ELEMENTS
VOLTAMETRY
WATER