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Anodic stripping voltammetry (ASV) using noble electrodes is based on the reduction of As3+ to As0, followed by its stripping or oxidation to As3+ or As5+ species, the two predominant forms of arsenic in water. The rapid and convenient ASV method can detect As(iii) at the low ppb level, but it is susceptible to interferences from various endogenous metals or organic compounds in waters. Electrode surface modification with metallic nanoparticles (NPs), carbonaceous nanomaterials (carbon nanotubes and graphene) and even enzymes (arsenite oxidase) can improve detection sensitivity and selectivity, while circumventing such interferences. All electrochemical methods aim for a detection limit below the World Health Organization guideline value of 10 ppb (133.3 nM). Despite numerous publications in this field during the last ten years with respect to novel electrode materials and electrolytes, reproducibility of electrochemical detection is still problematic and the analysis of arsenic in real ground-water samples is far from certainty and triviality. Considerable efforts are still needed to develop electrode materials and analytical procedures for reliable detection of arsenic with sub-ppb levels in the presence of endogenous toxic metals and organics in water matrices.

An analytical procedure for determining the relative amounts of ⁶⁰Co and its ⁶⁰Ni daughter in a radioactive cobalt source by means of chromatographic separation and radiometric and mass spectrometric detection was developed, optimized and assessed through two round robin exercises for nuclear forensic investigations. Solid phase extraction (EXC) using Ni resin (Eichrom) and ion exchange (IEC) using Dowex-1X8 (Acros Organics) chromatographic approaches were considered for separating Co and Ni. Decontamination factors of 25 and 2.8 × 10&#8310 were measured for EXC and IEC, respectively. Based on those results, only the IEC option was pursued. The effects of particle size, mass of resin, and degree of cross-linkage for decontamination performance were assessed, and the loading/eluting conditions were optimized. Canadian (CNSC, RPB, UL, RMC, AECL) and American (ANL) laboratories participated in two round robin exercises designed by the National Research Council of Canada to determine the suitability and limitations of the proposed methods. Age determination for freshly irradiated sources (