Intrinsic isotopic C labelling of polyphenols

The intrinsic isotopic labelling of plants with ¹³CO₂ is an effective method to generate highly labelled compounds using photosynthesis and avoiding labour-intensive complex organic syntheses. In this study, the intrinsic isotopic labelling of polyphenols in parsley, spinach and peppermint is shown for the first time. The plants were grown in an atmosphere where ¹²CO₂ was replaced by ¹³CO₂, in order to generate highly labelled compounds. The total content of ¹³C as well as the individual polyphenols were analysed by Isotopic Ratio-MS and HPLC–Iontrap-MSⁿ.     

早熟油菜氮素分配特征研究

通过15N标记方法研究氮素的吸收、分配、再分配与油菜早熟的内在关系。研究结果表明,早熟油菜品种中油116（ZY116）生育期比中晚熟油菜品种中双11号（ZS11）短9d,在营养生长期和生殖生长期分别短5d和4d。早熟品种ZY116在全生育期吸收的氮素比中晚熟品种ZS11更多的向籽粒中转移,而中晚熟品种ZS11则是花期吸收的氮素向角果皮中转移的更多,角果期氮素从角果皮转移到籽粒的更少,均达显著水平。早熟品种ZY116在营养生长阶段吸收的氮素在后期的分配速度明显快于ZS11,如ZY116苗期吸收的氮素从花期生长到角果期时再分配速度为3．22mg／d,从角果期生长到收获期时再分配速度为3．71mg／d,而ZS11分别为2．48mg／d和3．10mg／d。     

Rapid degradation of the mycotoxin patulin in man quantified by stable isotope dilution assays

The absorption and degradation of the mycotoxin patulin in man was quantified by using a recently developed stable isotope dilution assay. Application of this currently most sensitive method revealed a patulin content less than 200 ng l -1 in the blood serum of five consumers of apple juice. Likewise, no patulin was found in the serum of a volunteer, whose blood was drawn shortly after consumption of a juice containing a maximum tolerable amount of patulin. In further in vitro experiments, the degradation of patulin by reacting it with whole blood was investigated. After addition of 100 μg patulin to 9 ml blood, only 6.1% of the mycotoxin was detected after 2 min. It was concluded, therefore, that even high naturally occurring concentrations of patulin in foods are quickly degraded before reaching other tissues than the gastrointestinal tract.     

Dynamic and kinetic modeling of isotopic transient responses for CO insertion on Rh and Mn–Rh catalysts

Isotopic transient tracer techniques have been employed to study heterogeneous hydroformylation on Rh/SiO₂ and Mn–Rh/SiO₂. Pulse injection of D₂ and allowed tracing of the deuterium and CO incorporation pathway into the aldehyde product. The d₁- and d₂-propionaldehyde responses showed a double-peak, or two-hump, response to the D₂ pulse, while showed a single-hump response to the pulse. Analysis of the product responses to the D₂ pulse in CO/H₂/C₂H₄ and CO/H₂/C₂H₄/C₂H₅CHO suggests that the first hump of the d₁- and d₂-propionaldehyde responses was due to rapid H/D exchange with adsorbed propionaldehyde via enol intermediates. The decay of the second hump was due to reaction of adsorbed acyl with spillover hydrogen/deuterium. The response was due to CO insertion followed by acyl hydrogenation. Compartment modeling of the product responses from the and D₂ pulse inputs allowed determination of residence times of adsorbed intermediates, surface coverages of adsorbed intermediates, and the elementary rate constants for acyl hydrogenation and CO insertion. Elementary rate constants for acyl hydrogenation determined from this study were consistent with the value calculated by transition state theory (TST). The addition of Mn promoter to Rh/SiO₂ increased coverages of , , and and shifted the rate-limiting step for propionaldehyde formation. Acyl hydrogenation is the rate-limiting step on Rh/SiO₂ while CO insertion and acyl hydrogenation are both kinetically significant on Mn–Rh/SiO₂.     

同位素分析法在三山岛金矿的应用

三山岛矿区地下水质有海水、第四系水、基裂岩隙水、地下热水、淡水等。为了适应矿区生产的需要,需对水质进行分析。但是,常规的水质简分析法只能鉴别水的类型,不能提供其它资料,为此采用同位素分析法。该法不仅能验证水文地质研究提供的结果,还能提供水文地质研究不易取得的数据与资料,如地下水相对停留时间,不同成因不同成分的地下水补给源的补给量及其比例。     

Estimation of source contribution to nitrate loading in road runoff using stable isotope analysis

The nitrogen load was determined in road runoff during rainfall events. Moreover, nitrate isotopes analysis was conducted to determine the contribution of nitrates from atmospheric deposition and leaching from road dust. The concentrations of NO₃-N in road runoff were higher than those in atmospheric deposits for each rainfall event, except one event with a long antecedent dry weather period. The δ¹⁸O-NO₃ in road runoff was lower than in atmospheric deposits and higher than in leachate from road dust; however, no difference in δ¹⁵N-NO₃ was observed. By using δ¹⁸O-NO₃ as an indicator for evaluating NO₃-N sources in road runoff, contribution ratios of NO₃-N from road dust were estimated to be 14–22%, 23–25%, and 22–34% for Event 1 to Event 3, respectively. These results indicated that the NO₃-N from the atmosphere accounts for more than half of the NO₃-N in road runoff.     

Detection of counterfeit scotch whisky by H and O stable isotope analysis

Neat Scottish whiskies and the local source water used for and during whisky production have been analysed for their ²H and ¹⁸O isotopic composition by High Temperature Conversion–Isotope Ratio Mass Spectrometry (TC/EA–IRMS). With coefficients of determination R² for δ²H and δ¹⁸O of 0.71 and 0.88, respectively, measured δ²H and δ¹⁸O values for water used in the production of Scottish whisky were found to be well correlated with the δ²H and δ¹⁸O values observed for the corresponding whiskies. By plotting bulk ²H against bulk ¹⁸O isotope abundance data of authentic whisky and counterfeit whisky samples it was possible to discriminate between samples of authentic whisky and samples of counterfeit whisky.     

电感耦合等离子体质谱法测定硼同位素丰度

以硼同位素标准参考物质NISTSRM951配制的标准溶液,在优化的操作条件下对电感耦合等离子体质谱（ICP-MS）测定的硼同位素质量进行校正,求出校正因子,确定了样品的线性浓度范围。在同样的仪器条件下测定了硼同位素浓缩过程中样品三氟化硼甲醚络合物中的硼同位素丰度比,测定结果的相对标准偏差为1.095%。此外考查了仪器的稳定性。实验结果表明,本文建立的测定硼同位素丰度的方法“记忆效应”小,结果可靠,测量精度高。     

同位素稀释质谱法测定高放废液中的铀

用双同位素稀释质谱法测定高放废液中的微量铀,采用TBP/Kel-F粉反相分配色层法分离铀,双稀释剂分别为浓缩~(235)U及~(238)U,铀同位素丰度比的质谱测定相对标准误差优于0.1%,化学处理及质谱测定全流程铀的空白值为3×10~(-9)g,方法检测限对于铀为1×10~(-9)g,高放废液中微量铀测定结果不确定度为±2%。     

RADIOACTIVE OR NATURAL TRACER。TECHNIQUES FOR LEAK DETERMINING OF DAM ABUTMENT

Infiltration and localization of preferential infiltration zones at the dam abutment are measured using radioactive tracer tests of flow in boreholes,meanwhile interconnection between boreholes and the energing water points is analysed.The theory and practice of radioactive tracer synthetic detective method are described to give methods and calculation formulae used under the condition of stable flow in single well to measure permeability coefficient and hydrostatic heads.Major single hole techniques including measurement for seepage line,velocity,rate of seepage flow and relationship of recharge of groundwater in aquifers are introduced briefly.The possibilities offered by natureal tracers are analysed,uincluding electric-conduct,pH-value and temperature of water as well as stable isotopes(D,^18O) and tritium.Furthermore,the sensibilities of this theory and methods were confirmed by detecting seepage flow field of Xinanjiang Dam.