Determination of U isotope ratios in sediments using ICP-QMS after sample cleanup with anion-exchange and extraction chromatography

The determination of uranium is important for environmental radioactivity monitoring, which investigates the releases of uranium from nuclear facilities and of naturally occurring radioactive materials by the coal, oil, natural gas, mineral, ore refining and phosphate fertilizer industries, and it is also important for studies on the biogeochemical behavior of uranium in the environment. In this paper, we describe a quadrupole ICP-MS (ICP-QMS)-based analytical procedure for the accurate determination of U isotope ratios (²³⁵U/²³⁸U atom ratio and ²³⁴U/²³⁸U activity ratio) in sediment samples. A two-stage sample cleanup using anion-exchange and TEVA extraction chromatography was employed in order to obtain accurate and precise ²³⁴U/²³⁸U activity ratios. The factors that affect the accuracy and precision of U isotope ratio analysis, such as detector dead time, abundance sensitivity, dwell time and mass bias were carefully evaluated and corrected. With natural U, a precision lower than 0.5% R.S.D. for ²³⁵U/²³⁸U atom ratio and lower than 2.0% R.S.D. for ²³⁴U/²³⁸U activity ratio was obtained with less than 90 ng uranium. The developed analytical method was validated using an ocean sediment reference material and applied to an investigation into the uranium isotopic compositions in a sediment core in a brackish lake in the vicinity of U-related nuclear facilities in Japan.     

Comparison of ICP-MS and SIMS techniques for determining uranium isotope ratios in individual particles

The determination of uranium isotope ratios in individual particles is of great importance for nuclear safeguards. In the present study, an analytical technique by inductively coupled plasma mass spectrometry (ICP-MS) with a desolvation sample introduction system was applied to isotope ratio analysis of individual uranium particles. In ICP-MS analysis of individual uranium particles with diameters ranging from 0.6 to 4.2 μm in a standard reference material (NBL CRM U050), the use of the desolvation system for sample introduction improved the precision of ²³⁴U/²³⁸U and ²³⁶U/²³⁸U isotope ratios. The performance of ICP-MS with desolvation was compared with that of a conventionally used method, i.e., secondary ion mass spectrometry (SIMS). The analysis of test swipe samples taken at nuclear facilities implied that the performance of ICP-MS with desolvation was superior to that of SIMS in a viewpoint of accuracy, because the problems of agglomeration of uranium particles and molecular ion interferences by other elements could be avoided. These results indicated that ICP-MS with desolvation has an enough ability to become an effective tool for nuclear safeguards.     

A comparative study of234U/238U alpha-activity ratios determined by alpha-spectrometry and calculated from mass spectrometric data

²³⁴U/²³⁸U α-activity ratios determined by α-spectrometry (AS) and those calculated from the atom ratio data using the half-life values are compared in some of the isotopic reference materials of uranium and a few other uranium samples. For α-spectrometry, electrodeposited sources were prepared and a large area passivated ion implanted (IPE) detector (450 mm²) was used for recording the α-spectra. The isotopic composition of U was determined by thermal ionisation mass spectrometry (TIMS) and the recommended half-life values of²³⁴U and²³⁸U were used to calculate the α-activity ratio. It is observed that²³⁴U/²³⁸U α-activity ratios calculated from the atom ratio data are consistently high, with a mean difference of about 5%, when compared to the α-spectrometry results. This discrepancy warrants confirmation by a few more laboratories and suggests redetermination of the half-life values of²³⁴U and²³⁸U.     

Determination of uranium in marine sediment pore waters by isotope dilution inductively coupled plasma mass spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS) was used in an isotope dilution mode to assay small-volume (0.25 ml) sediment pore waters for their uranium contents, using ²³⁶U as the spike. The only pretreatment required was a simple dilution by a factor of 20, which gave sufficient volume for three replicate analyses per sample. Rapid and accurate results were obtained for a variety of samples and standards, ranging in concentration from 0.05 to 10 ng U ml^?1. A suite of 30 samples can be analysed in less than 6 h by this method. The relative standard deviation was better than 1.9%, with a detection limit, based on 3σ background, of 2 pg U ml^?1 in solution (40 pg ml^?1 in samples). Sea water is a difficult matrix for ICP-MS and thus the method is generally suitable for uranium determinations in many other sample solutions.     

Metabolism of <Superscript>14</Superscript>C-labelled and non-labelled sulfadiazine after administration to pigs

The behaviour of sulfadiazine (SDZ) and its metabolites was investigated by administering the ¹⁴C-labelled veterinary drug to fattening pigs. The excretion kinetics were determined after daily collection of manure. Two known metabolites, N-acetylsulfadiazine and 4-hydroxysulfadiazine, and two hitherto unidentified minor metabolites were recovered. Various mass spectrometric techniques such as parent, product ion scans and accurate mass measurement were used. The new compounds were identified as N-formylsulfadiazine (For-SDZ) and N-acetyl-4-hydroxysulfadiazine (Ac-4-OH-SDZ). The identification of SDZ, Ac-SDZ and For-SDZ was confirmed by comparison of the spectroscopic and chromatographic data of the synthesized authentic references. The identification of the hydroxylated compounds 4-OH-SDZ and Ac-4-OH-SDZ was performed by MSⁿ, and accurate mass measurements. Only 4% of the administered radioactivity remained in the pig after ten days and SDZ accounted for 44% of the 96% radioactivity excreted. More than 93% of the labelled compounds were detected and identified in the manure. The key analytical problem, namely a high concentration of matrix in sample extracts, was overcome by advanced measurement techniques and with the use of a suitable internal standard. The mean recoveries for all compounds were ≥96%. Linearity was established over a concentration range of 0.5 to 10,000 μg kg⁻¹ manure with a correlation coefficient ≥0.99. The same experiment was carried out simultaneously with non-labelled SDZ to obtain manure for outdoor soil experiments.     

Determination of compound-specific Hg isotope ratios from transient signals using gas chromatography coupled to multicollector inductively coupled plasma mass spectrometry (MC-ICP/MS)

MeHg and inorganic Hg compounds were measured in aqueous media for isotope ratio analysis using aqueous phase derivatization, followed by purge-and-trap preconcentration. Compound-specific isotope ratio measurements were performed by gas chromatography interfaced to MC-ICP/MS. Several methods of calculating isotope ratios were evaluated for their precision and accuracy and compared with conventional continuous flow cold vapor measurements. An apparent fractionation of Hg isotopes was observed during the GC elution process for all isotope pairs, which necessitated integration of signals prior to the isotope ratio calculation. A newly developed average peak ratio method yielded the most accurate isotope ratio in relation to values obtained by a continuous flow technique and the best reproducibility. Compound-specific isotope ratios obtained after GC separation were statistically not different from ratios measured by continuous flow cold vapor measurements. Typical external uncertainties were 0.16‰ RSD (n = 8) for the ²⁰²Hg^/198Hg ratio of MeHg and 0.18‰ RSD for the same ratio in inorganic Hg using the optimized operating conditions. Using a newly developed reference standard addition method, the isotopic composition of inorganic Hg and MeHg synthesized from this inorganic Hg was measured in the same run, obtaining a value of δ ²⁰²Hg = −1.49 ± 0.47 (2SD; n = 10). For optimum performance a minimum mass of 2 ng per Hg species should be introduced onto the column.     

Pitfalls in compound-specific isotope analysis of environmental samples

In the last decade compound-specific stable isotope analysis (CSIA) has evolved as a valuable technique in the field of environmental science, especially in contaminated site assessment. Instrumentation and methods exist for highly precise measurements of the isotopic composition of organic contaminants even in a very low concentration range. Nevertheless, the determination of precise and accurate isotope data of environmental samples can be a challenge. Since CSIA is gaining more and more popularity in the assessment of in situ biodegradation of organic contaminants, an increasing number of authorities and environmental consulting offices are interested in the application of the method for contaminated site remediation. Because of this, it is important to demonstrate the problems and limitations associated with compound-specific isotope measurements of environmental samples. In this review, potential pitfalls of the analytical procedure are critically discussed and strategies to avoid possible sources of error are provided. In order to maintain the analytical quality and to ensure the basis for reliable stable isotope data, recommendations on groundwater sampling, and sample preservation and storage are given. Important aspects of sample preparation and preconcentration techniques to improve sensitivity are highlighted. Problems related to chromatographic resolution and matrix interference are discussed that have to be considered in order to achieve accurate gas chromatography/isotope ratio mass spectrometry measurements. As a result, the need for a thorough investigation of compound-specific isotope fractionation effects introduced by any step of the overall analytical method by standards with known isotopic composition is emphasized. Finally, we address some important points that have to be considered when interpreting data from field investigations. Figure CSIA Principal (Carbon)     

ICP-MS测定土壤中铅同位素比值及地域差异性比较

建立用HNO_3-H_2O_2-HF体系微波消解前处理样品,利用电感耦合等离子体质谱测定土壤中铅同住素比值的方法,探讨并优化了影响测试结果的两种干扰因素.该方法中~(207)Pb/~(206)Pb和~(208)Pb/~(206)Pb的短期测量稳定性RSD分别达到0.12%和0.13%,长期测量的偏差分别在0.002和0.01以内,样品测量的最佳范围是10～40μg/L.采用标样-样品交叉法测定了湖南、湖北、云南、贵州、河南、福建、辽宁7个省的48个地区土壤中的铅同位素比值,结合聚类分析和主成分分析比较了各省土壤中同位素分布的差异,初步探讨了利用~(207)Pb/~(206)Pb和~(208)Pb/~(206)Pb比较烟叶产区的可能性.     

氧化石墨烯/壳聚糖微球吸附-电感耦合等离子体质谱法测定地质样品中痕量钽EI北大核心CSCD

建立了氧化石墨烯/壳聚糖微球吸附-电感耦合等离子体质谱法测定地质样品中痕量Ta的方法。合成了氧化石墨烯/壳聚糖微球,将其应用于地质样品中痕量Ta的分离富集,采用电感耦合等离子体质谱对富集后的试液进行测定。对氧化石墨烯含量、配体种类和浓度、pH、吸附时间、吸附剂用量等吸附条件和洗脱剂类型、体积、洗脱时间等洗脱条件进行了优化,在优化的条件下,对地质样品标准物质进行测定,Ta的方法检出限为2.0 ng/g,富集倍数为26.7倍。     

电感耦合等离子体串联质谱(ICP-MS/MS)法混合模式同时测定土壤中7种重金属元素

为高效、准确、批量对土壤中多元素进行同时检测,本文通过改善消解模式、载气流速,优化了质谱条件,采用电感耦合等离子体串联质谱法(ICP-MS/MS)测定土壤中7种重金属元素。样品经王水预消解,氢氟酸+高氯酸+硝酸消解,以103^Rh作为内标溶液消除基体干扰,在MS模式下通入氦气(即氦气模式),MS/MS模式下通入氧气(即氧气模式)消除质谱干扰的方式测定土壤中As、Pb、Cd、Cr、Ni、Cu、Zn 7种重金属元素。结果表明：当氦气流量为5.0mL/min,氧气流量为0.40mL/min时方法灵敏度和干扰消除效果最好。该方法的线性范围超过3个数量级,相关系数 r≥0.9999,检出限为0.01~1.00mg/kg,相对标准偏差(RSD)为1.5~10.2%。通过3个国家土壤一级标准物质(GBW07403a、GBW07404a、GBW07405a)对该方法进行了方法学验证,验证结果均在参考值范围内。     

Determination of Bromate in Bottled Drinking Water from Saudi Arabian Markets by HPLC/ICP-MS

The determination of bromate BrO₃ ^? in 50 different bottled drinking water samples collected from Saudi Arabian markets has been investigated using liquid chromatography inductively coupled plasma mass spectrometry (HPLC/ICP-MS). For analysis, samples were injected directly without any further pretreatment or dilution, using only a 50 μL injection volume. The method showed: detection limit of 0.5 μg/L, limit of quantification of 1.0 μg/L, 1.0 ? 200.0 μg/L linearity range (r² = 0.9998), relative standard deviation (%RSD) for reproducibility (inter-day precision) values of 14% and 4% for low and high concentration levels (10,100 μg/L), respectively. The results obtained for bromate showed that 30% of the samples are acceptable as US EPA standards (10 μg/L), 40% of the samples are acceptable as Gulf (Saudi Arabia) standards (25 μg/L), and almost 60% of the samples exceed the allowable limits for bromate in bottled drinking water.     

同位素稀释气相色谱/三重四极杆串联质谱法分析环境样品中的多氯萘

采用稳定同位素标记的多氯萘(PCNs)同类物为内标,建立了同位素稀释气相色谱/三重四极杆串联质谱技术测定环境样品中20种高关注的PCNs同类物的方法。结果表明:PCNs同类物的校正曲线在0.5~200 μg/L范围内线性良好(R²>0.99),检出限(LOD)为0.04~0.48 μg/L,相对标准偏差(RSD)小于15%。采用基质加标法评价该方法对实际环境样品中PCNs测定的回收率为45.2%~87.9%。为验证方法的适用性,以河流沉积物和再生铝冶炼排放的烟道气样品为对象,利用所建立的方法测定了20种PCNs同类物,并将结果与高分辨气相色谱/高分辨质谱方法的测定结果进行了比对,两种方法测定结果的RSD为0.5%~41.4%,表明所建立的同位素稀释气相色谱/三重四极杆串联质谱方法可用于实际环境样品中PCNs的定性、定量分析。     

茶叶和蔬菜中铅的同位素稀释电感耦合等离子体质谱的测定

采用同位素稀释电感耦合等离子体质谱(ID-ICP-MS)法测定了铅的含量,通过对茶叶标准物质(GBW-07605)中铅的测定,考察了方法的准确度和精密度,比较了同位素稀释法与普通外标定量法的测定结果。在5mLHNO3～0.5mLHF～1mLH2O2的消解体系中,ID-ICP-MS法测量茶叶中铅的回收率可达97.7%,相对标准偏差(RSD)小于1.2%。实验对市售的12种茶叶和10种蔬菜中Pb进行测定,铅含量符合相应国家标准的样品分别占总样品数的83%和90%。该法适合于植物样品中微量铅的测定。     

电感耦合等离子体质谱测定地质样品中Pb同位素比值

铅有 4个天然的同位素 ,由于放射衰变、宇宙的辐射及人类的活动 ,使 2 0 6Pb/2 0 4 Pb,2 0 7Pb/2 0 4 Pb及2 0 8Pb/2 0 4 Pb值在自然界中呈现相应的变化 ,而这种变化使得铅同位素成为一种有效的示踪手段和地质年代学研究的工具 ,同时在环境质量监控、放射性污染追踪及人类社会的变迁等方面有着广泛应用 .热电离质谱 (TIMS)分析技术对于大多数的同位素比值测定具有极高的精密度和准确度 ,但对于铅的测定由于难以获得一个高度浓缩且稳定不变的同位素作为内标进行质量偏移校正 [1] ,使其测定的准确度受到影响 .Rehkamper等 [2 ,3 ] 研究了…     

Determination of some acidic drugs in surface and sewage treatment plant waters by capillary electrophoresis-electrospray ionization-mass spectrometry

We describe an analytical method involving solid-phase extraction (SPE) and capillary zone electrophoresis-electrospray ionization-mass spectrometry (CZE-ESI-MS) for determining some pharmaceutical compounds - naproxen, clofibric acid and bezafibrate - in real water samples. The electrospray parameters were optimized to maximize sensitivity. When a mixed aqueous-organic solvent and CZE-ESI-MS were used to analyze these drugs in water samples, the capillary was coated with hexadimethrin bromide (HDB) to permanently reverse the EOF. The method was developed from off-line SPE-CZE-MS and was validated with surface water. The detection limits were 100 ng.L(-1) for all analytes. The method was applied to analyze water samples from the influent and effluent of a sewage treatment plant. A liquid-liquid extraction step was required before SPE, and the compounds studied were found, some of them between detection and quantification limits.     

同位素稀释三重串联四级杆质谱法测定鱼组织中24种多环芳烃

采用气相色谱-三重串联四级杆质谱联用技术测定了鱼组织中24种多环芳烃(PAHs).将冻干鱼组织样品加入同位素内标后,用加速溶剂萃取法(ASE)进行提取,提取液采用凝胶排阻色谱(GPC)和固相萃取(SPE)联用进行净化.采用二氯甲烷为提取溶剂,100℃下提取,以二氯甲烷作为GPC的流动相,在3.5 mL/min流速下,收...     

Determination of 206/207Pb isotope ratios by ICP-MS in particulate matter from the north sea environment

Summary The determination of lead isotope ratios can be used for source and pathway characterization of lead in the environment. The suitability of inductively coupled mass spectrometry (ICP-MS) was evaluated for the measurement of ^206/207Pb isotope ratios in several marine compartments as marine aerosols from different source regions and suspended particulate matter from the North Sea. Two different ICP-MS systems were used to carry out these investigations. First optimization studies have been performed to yield a sufficient precision (RSD <0.5%) in combination with a reasonable measuring time. This study has been carried out using the standard reference material NBS 981 with certified lead isotope ratios. Furthermore, it could be shown for marine environmental samples, that a precision of less than 0.5% RSD is attainable for counting rates of above approximately 50000 cps. As the following measurements of lead isotope ratios in marine aerosols from main source regions surrounding the North Sea demonstrated, this precision is sufficient to determine significant differences due to the origin of atmospheric lead. The analysis of aerosol samples revealed isotope ratios varying from as low as 1.10, which is close to that ratio for leaded gasoline in Europe to near background (modern lead) values of 1.20. The lead isotope ratios for the investigated suspended particulate matter ranges between 1.13 and 1.18. These values can be related to the solid discharge, the urban density and anthropogenic activity of the drainage basin.