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background The lead isotope ratios (LIR) differ among different sourced samples. Previous domestic and oversea studies on source tracing by LIR in human blood or urine mainly focused on the comparison of blood or urine samples from the same or different individuals, while few comparisons between biological and environmental samples, and the reported relative standard deviations (RSDs) of the main LIR (207/206Pb and 208/206Pb) fluctuate widely from 0.3% to 1%. Objective To optimize inductively coupled plasma mass spectrometry (ICP-MS), obtain a better RSD, and determine LIRs of human blood, urine, and related environmental samples. Methods The ICP-MS was optimized for operating conditions and parameters according to the sensitivity and RSD of LIR. The study subjects were 40 lead-exposed workers in a lead-acid battery factory and 2 lead poisoned children in a hospital. The samples included 40 blood and 40 urine samples from the workers before shift, 4 dust samples and 2 water samples in the workplace on the same day before shift, 2 blood and 3 urine samples from the children before hospital admission due to lead-poisoning, and 4 urine samples after medical treatment. After heating and acid digestion, the LIR (207/206Pb and 208/206Pb) of biological and environmental samples were determined by the optimized ICP-MS method. t-test and two-dimensional traceability graphics were adopted to analyze the detection results. Results The calibrated RSDs of the LIR (207/206Pb and 208/206Pb) of lead isotope standard solution were 0.11% and 0.08% respectively, and the NIST-SRM-981 actual values were 0.91531±0.00097 and 2.1670±0.0017, respectively. When the total concentration of lead was greater than 5 μg·L−1, the RSD of each isotope ratio was stable gradually; when the total concentration of lead was between 10-80 μg·L−1, the RSD was below 0.20%. There were statistically significant differences in the blood and urine LIR (207/206Pb and 208/206Pb) of the lead-exposed workers (t=5.831, P<0.001; t=21.021, P<0.001), the LIR (207/206Pb and 208/206Pb) between workplace dust samples and workers’ urine samples (t=−6.879, P=0.038; t=12.521, P<0.001), and the 208/206Pb between workplace dust samples and workers’ blood samples (t=−10.46, P<0.001), except the 207/206Pb between workplace dust samples and workers’ blood samples (t=−0.12, P=0.912). In the patients afflicted with lead poisoning, the projection points of LIR of blood and urine samples from the same individual were not at the same level in the two-dimensional model, nor was the LIR of urine samples before and after medical treatment of the same individual. Conclusion The optimized ICP-MS can control the RSD of main LIR (207/206Pb and 208/206Pb) below 0.20%. There are differences in the LIR distributions of different samples.
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An analytical method was developed for determination of low-level uranium isotopes in vegetation samples. Dry ashing method was employed to decompose organic matters of vegetation. The sample ash was further digested using multiple acids. Uranium in the prepared sample solution was separated and purified by an extraction chromatography using UTEVA resin. The chemical recovery of uranium in the separation procedure was more than 94% , and more than 99% of Na, K, Ca and other matrix elements and interfering elements were removed. Three natural uranium isotopes were finally measured with high sensitivity ICP-MS/MS. The detection limits of the method for 238U, 235U, 234U were 3. 05, 0. 34 and 0. 04 pg/g, respectively. The detection limits for 238U and 235U were 10 times better than the reported values. Analysis result of U in GBW-10046 standard reference material was in good agreement with reference value, indicating that this method was reliable. The method was successfully applied to determination of uranium isotopes in the vegetation samples collected in Xi′an region, and it was found that the uranium concentrations and isotopic ratios in these vegetation samples fall well into natural level, and there was no significant artificial uranium contamination. This was the first survey of the three natural uranium isotopes in vegetation samples in this region.
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Se analizaron muestras de un suelo ferralítico rojo de la Estación Experimental Juan Tomás Roig de la Universidad de Ciego de Ávila, sometido a dos rotaciones de cultivo y cuatro sistemas de fertilización fosfórica. El objetivo fue evaluar, mediante la dilución isotópica del 32P, los parámetros estáticos del fósforo (P) en un suelo que recibió fertilizante fosfórico por dos métodos de aplicación (en bandas y a voleo) durante varios años. Se utilizó un método radioquímico de laboratorio usando una disolución marcada con 32P libre de portador, basado en el intercambio isotópico entre los fosfatos de los sólidos y la solución del suelo. Las muestras de suelo se analizaron en los laboratorios del Departamento del Comisariado de Energía Atómica, Francia. Se determinaron los factores cantidad (E1) como el P isotópicamente intercambiable en un minuto, intensidad (Cp) como la concentración de P en la solución del suelo y capacidad como la relación E1/Cp. La evaluación isotópica mediante 32P indicó que el suelo necesita de aplicaciones de P altas y en bandas para alcanzar valores de E1 y Cp adecuados para la nutrición de los cultivos agrícolas. Con la fertilización en bandas se logró un efecto acumulativo del P en el suelo después de tres ciclos de rotación de cultivos, que permitió incrementar su disponibilidad para las plantas. El factor capacidad resultó muy alto en todas las muestras de suelo, lo cual indica que el suelo mantiene una reserva de P que es difícilmente intercambiable con el P de la solución del suelo
Soil samples from a red ferralitic soil from the "Juan Tomás Roig" Experimental Station, belonging to Ciego de Avila University were analyzed under two crop rotations and four phosphoric fertilization systems. The objective was to evaluate, through the 32P isotopic dilution, phosphor (P) static parameters in a soil that has received P fertilizer through two placement methods (banding and broadcasting) for several years. A radiochemical laboratory method using a 32P free-carrier solution as a tracer based on isotopic exchange between solid phase and soil solution phosphate ions was used. Soil samples were analyzed at the CEA Department laboratories, in Francia. Quantity (E1), as isotopic exchangeable P at one minute, intensity (Cp), as P concentration in soil solution, and capacity, as (E1/Cp), factors were determined. 32P isotopic evaluation indicated that the soil needs high banding P application to reach adequate E1 and Cp values for crop nutrition. A cumulative P effect in the soil through banding fertilization after three crop rotation cycles was obtained, which allows to increase plant P availability. The capacity factor was very high in all soil samples, indicating that soil maintains a P reserve that is difficult to exchange with the phosphor present in the soil solution
ABSTRACT
The analysis of stable nitrogen isotopic composition (δ15 N) of individual amino acid was recognized as an effective method for estimating the trophic level of organisms and detecting the nitrogen flow in food webs. In this study, we evaluated a two-stage procedure of esterification followed by acylation, in which biological samples underwent hydrolysis in acid and the released individual amino acids were derivative into the corresponding N-pivaloyl-iso-propyl ( NPP ) esters for gas chromatography-combustion-isotope ratio mass spectrometric ( GC-C-IRMS) analysis. A total of 13 kinds of individual amino acid derivatives were baseline separated on a nonpolar gas chromatography column (DB-5ms). The amount of sample for each test was not less than 20 ng N on column. High correlations were observed between the δ15 N values respectively obtained by GC-C-IRMS and element analysis-isotope ration mass spectrometry (EA-IRMS). Furthermore, the mean precision of this method was better than 1‰. Cation-exchange chromatograph was used to purify the samples, and the difference of the detection δ15 N values before and after purification by the resin was within 1‰. This method was applied to estimate the trophic level of various natural freshwater organisms from Aha Lake. The present study provided a new idea for the application of stable nitrogen isotope (δ15 N ) in the trophic level estimation of organisms and metabolism analysis of amino acid.
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A method was developed for analyzing the stable carbon isotope ratio of five volatile components ( Ethanol, Glycerol, Acetic acid, Ethyl lactate, 2-methyl-butanol ) in wine using gas chromatography-combustion-isotope ratio mass spectrometer ( GC-C-IRMS ) . The sample injection volume was less than 0. 5 μL, and the analytical time of each run was less than 14 min. The precision of this method was 0. 08‰-0. 25‰ for analyzing standards, while 0. 09‰-0. 36‰ for wine samples. Compared to element analysis-isotope ratio mass spectrometry ( EA-IRMS) results, the deviations were lower than 0. 5‰. Fifty-four wine samples from France, Australia, America and China were considered. The δ13 C of five volatile components were measured using GC-C-IRMS. Discriminant analysis ( DA) was employed for analyzing the geographical origin traceability of selected wine. The result indicated that δ13 C of volatile components could be used to distinguish the origin of wines. The method was shown to be effective in improving detection of the origin traceability of wine.
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Water quality, the carbon isotope ratio of suspended particulate organic matter (POM), and limiting nutrients were investigated at seven surface and bottom seawater stations in Gamak Bay, South Korea, to evaluate the effectiveness of counter-measures to organic matter increase. The increase in surface water COD in Gamak Bay appear to be the result of phytoplankton growth, which is consistently limited by nitrogen (N) or phosphorous (P), but not by silicon (Si). High chlorophyll a concentrations seem to be caused by freshwater inputs of N and P associated with wastewater in the northern and northeastern portions of the Bay, and by the inflow of NH4-N and P associated with the digestion of organic matter from the bottom layer in western areas. To regulate the increase of organic matter in Gamak Bay, controlling phytoplankton growth, particularly by regulating the input of N or P, may be more important than controlling the input of terrestrial organic matter.