RESUMEN
An online separation and preconcentration method, using an automated flow injection setup and solid phase extraction followed by ICP-MS/MS, was developed for the analysis of 90Sr, and U, Am and Pu isotopes in various liquid sample matrices. The radionuclide analytes were separated from interferences and complex matrices using DGA-branched resin and Sr resin, then specific gases were used in the reaction/collision cell in the ICP-MS/MS to measure the different analytes. The system requires smaller sample volumes (10 mL), less sample preparation and shorter processing time (46 min per sample) compared to traditional radiometric and other MS techniques. Based on a 10 mL sample, the limits of detection were 1.48 pg L-1 (8257 mBq L-1) for 90Sr, 1.75 pg L-1 (0.40 mBq L-1) for 234U, 0.65 pg L-1 (77.65 mBq L-1) for 241Am, and 0.56 pg L-1 (1.25 mBq L-1) for 239Pu when all target analytes were measured in one analysis. The analytical figures of merit were evaluated for a range of sample matrices including lake water, seawater and urine and were comparable to those reported in the literature. This online system thus provides a novel, fully automated analytical tool with faster analysis time, smaller sample requirements, minimum sample preparation, low detection limits and the flexibility to handle single and multiple measurements of various radionuclides.
Asunto(s)
Plutonio , Contaminantes Radiactivos del Agua , Plutonio/análisis , Radioisótopos de Estroncio , Espectrometría de Masas en Tándem , Contaminantes Radiactivos del Agua/análisisRESUMEN
Concentrations of metals in hair are used often to develop pharmacokinetic models for both animals and humans. Although data on uptake are available, elimination kinetics are less well understood; stable isotope tracers provide an excellent tool for measuring uptake and elimination kinetics. In the present study, methylmercury concentrations through time were measured in the hair and blood of mink (Neovison vison) during a controlled 60-d feeding experiment. Thirty-four mink were fed a standard fish-based diet for 14 d, at the end of which (day 0), 4 mink were sacrificed to determine baseline methylmercury (MeHg) concentrations. From day 0 to day 10, the remaining mink were fed a diet consisting of the base diet supplemented with 0.513 ± 0.013 µg Me(199) Hg/g and 0.163 ± 0.003 µg Me(201) Hg/g. From day 10 to day 60, mink were fed the base diet supplemented with 0.175 ± 0.024 µg Me(201) Hg/g. Animals were sacrificed periodically to determine accumulation of Me(201) Hg in blood and hair over the entire 60-d period and the elimination of Me(199) Hg over the last 50 d. Hair samples, collected from each mink and cut into 2.0-mm lengths, indicate that both isotopes of MeHg appeared in the hair closest to the skin at approximately day 10, with concentrations in the hair reaching steady state from day 39 onward. The elimination rate of Me(199) Hg from the blood was 0.05/d, and the ratio of MeHg in the hair to blood was 119. A large fraction of MeHg (22% to >100%) was stored in the hair, suggesting that in fur-bearing mammals the hair is a major route of elimination of MeHg from the body.
Asunto(s)
Dieta , Cabello/química , Compuestos de Metilmercurio/sangre , Compuestos de Metilmercurio/metabolismo , Animales , Cabello/crecimiento & desarrollo , Marcaje Isotópico , Masculino , Espectrometría de Masas , Isótopos de Mercurio/química , Visón , Factores de TiempoRESUMEN
Total Hg, methyl-Hg (MeHg) and Se levels were measured in the brain of river otters (Lontra canadensis) and wild mink (Mustela vison) carcasses collected from Nova Scotia, Canada. Total Hg concentrations in the otters' brain were highly variable, ranging from 0.3 to 18.0 microg/g dw and were significantly higher in animals caught from inland areas of the province versus coastal animals. Similarly, inland otters contained significantly more MeHg in the brain than did coastal otters. MeHg was highly correlated with total Hg in both inland and coastal otters and represented on average approximately 82% of the total Hg. Selenium concentrations in the otter brain ranged from 1.0 to 7.8 microg/g dw but unlike Hg, there was no significant difference in Se levels between inland and coastal otters. There was a significant positive relationship between Se and total Hg concentrations in the otters with the molar ratio of Se:Hg approximately 1:1 for animals having an Hg concentration>18 nmol/g dw. The non-random sampling protocol for the mink precluded extensive statistical analysis of the data. However, unlike otters, virtually all (i.e. 98%) of the total Hg in mink brain was present as MeHg in both inland and coastal mink. Also unlike the otter results, Se concentrations showed no relationship with either total or MeHg in both inland and coastal mink. The data suggest that mink and otters may have different mechanisms for managing high levels of Hg in the brain.
Asunto(s)
Encéfalo/metabolismo , Mercurio/metabolismo , Visón/metabolismo , Nutrias/metabolismo , Selenio/metabolismo , Contaminantes Químicos del Agua/análisis , Animales , Encéfalo/efectos de los fármacos , Monitoreo del Ambiente , Agua Dulce , Mercurio/toxicidad , Nueva Escocia , Selenio/toxicidad , Contaminantes Químicos del Agua/metabolismo , Contaminantes Químicos del Agua/toxicidadRESUMEN
Total mercury (Hg) concentrations were measured in the fur, brain and liver of wild mink (Mustela vison) and river otters (Lontra canadensis) collected from eastern and Atlantic Canada. Total Hg concentrations in fur were strongly correlated with levels in the brain and liver. There was no difference in tissue concentrations between male and female mink; however, female otters had significantly higher fur, brain and liver Hg levels than males. Similarly, there was not a significant relationship between Hg concentration and age of mink, whereas in otters, Hg concentrations in all three tissues decreased significantly with age. In both species, only a very small percentage of the variability in Hg concentration was explained by age. After adjusting the data for site-to-site differences in Hg levels, Hg concentrations in the fur of mink infected by the parasite, Dioctophyma renale, were found to be significantly higher than Hg levels in uninfected mink.
Asunto(s)
Monitoreo del Ambiente/métodos , Mercurio/análisis , Visón/metabolismo , Nutrias/metabolismo , Contaminantes Químicos del Agua/análisis , Envejecimiento/fisiología , Animales , Química Encefálica , Canadá , Femenino , Cabello/química , Hígado/química , Masculino , Mercurio/metabolismo , Compuestos de Metilmercurio/análisis , Compuestos de Metilmercurio/metabolismo , Contaminantes Químicos del Agua/metabolismoRESUMEN
The use of stable isotopes coupled with inductively coupled plasma-mass spectrometry provides a unique opportunity to investigate pathways of metals in aquatic invertebrates. In this study, the simultaneous uptake and elimination of cadmium (Cd) in stream-dwelling caddisfly (Trichoptera: Hydropsychidae) larvae was measured in laboratory experiments with stable isotopes of Cd. In one experiment, animals were exposed to low levels (0.5 microg/L) of 114Cd in filtered river water and uptake was measured for 9 d, followed by 9 d during which the larvae were exposed to either 114Cd, 113Cd, or filtered river water. In a second experiment, the initial exposure concentration of 114Cd varied from 0.1 to 1.6 microg/L for 5 d, followed by 5 d during which the larvae were exposed to the same respective levels of 113Cd. The purpose of the two experiments was to test whether or not elimination of 114Cd from Hydropsyche larvae was the same in the presence or absence of Cd in the water and also whether or not elimination rates were dependent on exposure concentration. The results indicated that elimination of Cd by Hydropsyche larvae (elimination rate constant approximately 0.21-0.24/d) in the presence of Cd in the water was the same as the depuration when no metal was present. Furthermore, the elimination rate was independent of exposure concentrations, ranging between 0.1 and 1.6 microg/L. Thus, the stable isotope tracer technique enabled the simultaneous measurement of uptake and elimination of Cd in hydropsychid larvae and may have the potential to facilitate the labeling of various compartments (e.g., water, sediment, and food) in the aquatic environment.