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Abstract: Fifty-eight brands of balsamic vinegars were analyzed for lead concentrations and isotopic compositions (204Pb, 206Pb, 207Pb, and 208Pb) to test the findings of a previous study indicating relatively high levels of lead contamination in some of those vinegars — more than two thirds (70%) of them exceeded California''s State Maximum Level (34μg/L) based on consumption rates ≥0.5μg Pb per day. The Lead isotopic fingerprints of all those vinegars with high lead concentrations were then found to be primarily anthropogenic. This isotopic analysis unquestionably reveals multiple contamination sources including atmospheric pollutant Pb and an unidentified contamination source, likely occurring after grape harvest. Organically grown grape vinegars display the same Pb content and isotopic signatures as other vinegars. This implies that pesticides might not be a significant source of pollutant Pb in vinegars. A significant post-harvest contamination would be inherited from chemicals added during production and/or material used during transport, processing or storage of these vinegars. This is consistent with the highest Pb levels being found in aged vinegars (112±112μg/L) in contrast to other vinegars (41.6±28.9μg/L) suggesting contamination during storage. It is, therefore, projected that lead levels in most vinegars, especially aged balsamic and wine vinegars, will decrease with improvements in their manufacture and storage processes consequential to recent concerns of elevated levels of lead in some vinegars. [Copyright &y& Elsevier]

Abstract: There are increasing concerns with elevated levels of Cr(VI) in the environment because it is a strong oxidant, corrosive, and carcinogenic. The concerns extend to the presence of Cr(VI) in many aquifers in California and elsewhere, where relatively high levels have been attributed to both industrial pollution and natural processes. The authors have, therefore, determined if natural redox processes contribute to the presence of high Cr(VI) concentrations (6–36μgL−1) in an aquifer in central California relative to non-detectable concentrations (<0.1μgL−1) in an adjacent aquifer. Specifically, the distribution and the redox speciation of dissolved (<0.45μm) Cr have been compared with those of particulate Mn and Fe oxy-hydroxides in sediments, using X-ray absorption spectroscopy at the Mn and Fe L-edges. The analyses show a correlation between the presence of dissolved Cr(VI) and Mn (hydr)oxide minerals, which are the only common, naturally occurring minerals known to oxidize Cr(III) in laboratory experiments. This covariance substantiates the results of those experiments and previous field studies that indicate natural oxidation mechanisms might account for the relatively high levels of Cr(VI) in the study site, as well as for elevated concentrations in other aquifers with similar biogeochemical conditions. [Copyright &y& Elsevier]

Abstract: We investigated interference effects on the analysis of silver in estuarine and oceanic waters using on-line high resolution inductively coupled plasma mass spectrometry (ICP-MS). A mini-column packed with a strong anion exchange resin (Dowex 1-X8) was used in a flow-injection system to separate and concentrate silver from the saline samples prior to on-line determination by ICP-MS. A series of analyses showed the concentrations of silver measured in San Francisco Bay estuary and the North Pacific that had been acidified (pH<2) and stored for periods of 1–2 years were 10–70% lower than those measured in aliquots of those samples after ultraviolet (UV) irradiation. Additional silver released after UV irradiation of the estuarine waters, but not the ocean waters, was positively correlated (r =0.77, simple linear correlation) with chlorophyll-a concentrations, but not with dissolved organic carbon (DOC) concentrations. Spatial distributions of chlorophyll-a and UV-released silver also exhibited similar patterns along a salinity gradient in the San Francisco Bay estuary, suggesting an in situ biogenic source of the interferent for the silver measurements. [Copyright &y& Elsevier]

Lead concentrations of 59 different types of vinegars (15–307 μg l-1 in balsamic vinegars and 36–50 μg l-1 in wine vinegars) were determined using both inductively coupled plasma mass spectrometry (ICP-MS) and graphite furnace atomic absorption spectrometry (GFAAS). Although the precision of direct analyses, following simple aqueous dilutions, with either instrumental method was poor; that precision, following nitric acid and/or hydrogen peroxide digestions, markedly improved with either instrument and the values obtained with the two instruments were in good agreement. The efficacy of different digestions, including (1) nitric acid using a heating block, with or without addition of hydrogen peroxide and (2) mixtures of nitric acid and hydrogen peroxide using ultraviolet (UV) photolysis, were then assessed. The latter procedure was found to be much faster and more efficient, but it was limited by the relatively high levels of contaminant lead in hydrogen peroxide. Consequently, it is recommended that lead concentrations in vinegar be measured following a nitric acid digestion and UV photolysis to oxidize all organic matter before ICP-MS or GFAAS analysis; and it is further recommend that the thermal settings for the latter analyses be adjusted to account for the apparent presence of relatively volatile organolead compounds in vinegar digests. [Copyright &y& Elsevier]

The measured concentrations of cadmium, cobalt, copper, nickel, lead, zinc, and manganese in acidified (pH<2) estuarine water samples analyzed for total dissolved trace metal concentrations using on-line chelating resin column partitioning with inductively coupled plasma-mass spectrometry (CRCP-ICP-MS) were compared to those analyzed by graphite furnace atomic absorption spectrometry (GFAAS) after liquid–liquid extraction using a combination of 1-pyrrolidinedithiocarbamate/diethyldithiocarbamate (PDC/DDC). Although there was good agreement between the two sets of analyses for cadmium, lead, manganese, and zinc concentrations, those of cobalt, copper, and nickel determined by CRCP-ICP-MS were found to be 10–20% lower than those determined by solvent-extraction GFAAS. The different yields were positively correlated (R>0.961, simple linear regression) to the dissolved organic carbon (DOC) concentration of the samples. Good agreement between the two methods for cobalt and copper was achieved after ultraviolet (UV) digestion of the acidified samples. Samples collected from the South Bay of the San Francisco Estuary with high DOC showed the greatest difference for cobalt, copper, and nickel which is tentatively attributed to complexation with humic material for copper and cobalt and strong synthetic chelating agents such as ethylenediaminetetraacetic acid (EDTA) for nickel. This is consistent with previous studies on copper, nickel and cobalt complexation in this region. We recommend UV digestion of acidified estuarine samples prior to multi-element analysis by chelating resin flow injection ICP-MS methods. [Copyright &y& Elsevier]