稳定同位素标记3,5-二硝基水杨酸肼-15N2的合成

本文提出简便的方法合成3,5-二硝基水杨酸肼-15N2,即以水杨酸为前体,与硝酸钾-15N硝化得到3,5-二硝基水杨酸-15N2,再经过酯化,肼解反应得到目标产物。以消耗K15NO3计算,3,5-二硝基水杨酸肼-15N2的总收率为55.5%。产品结构经质谱和核磁共振波谱等表征确定,15N的同位素丰度为99.2 atom%15N,色谱纯度为97.3%,可作为食品安全领域检测用同位素内标试剂。     

稳定同位素标记3,5-二硝基水杨酰肼-~(15)N_2的合成

提出简便的方法合成3,5-二硝基水杨酰肼-15N2,即以水杨酸为前体,与硝酸钾-15N硝化得到3,5-二硝基水杨酸-15N2,再经过酯化、肼解反应得到目标产物。以消耗K15NO3计算,3,5-二硝基水杨酰肼-15N2的总收率为55.5%。产品结构经质谱和核磁共振波谱等表征确定,15N的同位素丰度为99.2 atom%15N,色谱纯度为97.3%,可作为食品安全领域检测用同位素内标试剂。     

硝基甲烷-~(15)N的合成

以丰度为98.7 atom%的Na15NO2为同位素原料,与硫酸二甲酯反应合成了硝基甲烷-15N,方法简便,同位素转化率为75%,纯度为98.8%,丰度为98.56 atom%。     

1-甲基-2,4,5-三硝基咪唑(MTNI)的合成

以4-硝基咪唑为原料,经硝化、热重排、甲基化等反应合成1-甲基-2,4,5-三硝基咪唑(MTNI),总收率19.4%,纯度>98%,经红外光谱、核磁共振、元素分析等方法表征其结构。研究了反应温度、反应时间等因素对1-甲基-2,4-二硝基咪唑(MDNI)合成及收率的影响,得到了较优的工艺条件:n(2,4-二硝基咪唑)∶n(碘甲烷)=5∶9,反应温度40~45℃,反应时间8h。对硝化反应条件进行了研究,确定了适宜反应时间为1h,反应温度为95℃。     

稳定同位素标记灭蝇胺-氨基-15N2的合成

根据天然丰度合成文献和检测内标的要求,确定15N标记灭蝇胺的结构和合成路线。以三聚氯氰为原料与氨水-15N反应得到2,4-二氨基-15N2-6-氯-1,3,5-三嗪,后者与环丙胺反应,两步生成目标产物。使用碳酸钠代替部分氨水,氨水利用率明显提高(从59.0%提高到80.0%)。以消耗的氨水-15N计算,灭蝇胺-15N2的总收率为68.1%(以三聚氯氰计)。产品结构经质谱和核磁共振波谱等表征,15N的同位素丰度为98.8%15N,色谱纯度为99.7%。以灭蝇胺-氨基-15N2产品为检测内标,高效液相色谱-电喷雾串联质谱检测灭蝇胺,在0.2~5 mg/kg时,线性关系良好(R=0.999 95),可作为食品安全领域的检测内标试剂。     

液相色谱-质谱联用法测定动物血浆中~(15)N标记氨基酸的同位素丰度

建立了液相色谱-质谱联用(LC-MS)测定血浆中稳定同位素~(15)N标记的甘氨酸、谷氨酸、天冬氨酸和尿素同位素丰度的方法。待测动物血浆样品经丙酮提取,氮吹浓缩后,用液相色谱电喷雾质谱(LC-ESI-MS)进行检测。以乙腈和质量分数为0.2%甲酸水溶液为流动相进行洗脱,经亲水色谱柱分离,在选择离子模式(SIM)下监测特定质荷比的上述四种待测物,依据测得的峰强度计算每种待测物的同位素丰度。通过对已知同位素丰度的甘氨酸-~(15)N、谷氨酸-~(15)N、天冬氨酸-~(15)N和尿素-15N2进行验证,相对偏差在0.7%以内。方法具有样品前处理简单、检测耗时少、表征结果准确,一次进样可同时测定血浆中稳定同位素标记甘氨酸-~(15)N、谷氨酸-~(15)N、天冬氨酸-~(15)N和尿素-15N2的同位素丰度等优点。     

1,4-二硝基咪唑的合成及其热分解

用二步反应合成1,4-二硝基咪唑(1,4-DN I),即先用乙酸酐对4-硝基咪唑3位上的N进行N-酰化,再通过硫酸-乙酸酐-硝酸钠混合液对酰化产物进行硝化合成1,4-二硝基咪唑,通过正交实验对合成工艺进行了优化,得到了较优的工艺条件:4-硝基咪唑、浓硫酸、硝酸钠、乙酸酐的摩尔比为2∶3∶8∶15,反应温度30~40℃,反应时间3 h。用DSC研究了1,4-DN I的热分解。     

N-苄基-2,4-二硝基咪唑的合成及其亲核取代反应

以2,4-二硝基咪唑为原料,经N-苄基保护合成出N-苄基-2,4-二硝基咪唑,并研究了其亲核取代反应,结果表明-N3、-F、-OCH3可以高收率的取代2位硝基,产物经核磁、质谱、元素分析进行了表征。     

对乙酰氨基酚-2-13C的合成及表征

以乙酸-2-~(13)C与N,N'-羰基二咪唑为原料,反应得到中间体N-乙酰基咪唑-2-~(13)C,该中间体进一步与对氨基苯酚反应得到对乙酰氨基酚-2-~(13)C。考察了反应温度和反应时间对对乙酰氨基酚-2-~(13)C收率的影响。结果表明:合成产物的最佳反应温度和时间分别为40℃和12h。产物经GC-MS、FTIR、1HNMR和~(13)CNMR进行结构表征。对乙酰氨基酚-2-~(13)C的气相色谱纯度99%,同位素丰度为98.7%,总产率为87%,合成的产物可作为同位素内标物在定量分析测试中使用。     

4,5-二硝基咪唑铵盐的合成及其热分解研究

以咪唑为原料,通过硝硫混酸硝化合成出4,5-二硝基咪唑,再经过氨基化制得4,5-二硝基咪唑铵盐(4,5-ADNI)。红外光谱、核磁共振、元素分析、质谱等分析方法表征了结构,测定了4,5-二硝基咪唑铵盐的密度、爆压和爆速。用DSC研究了4,5-二硝基咪唑铵盐的热分解,熔点为84.5℃,表明其稳定性良好。     

Hydrogen isotope exchange on Pd/NaY and Pd/HY zeolites

Mass spectrometry and FTIR were employed to monitor the isotopic exchange of various types of zeolite protons with D₂ at 21 °C. Discrete groups of protons are differentiated by their exchange kinetics. Protons in close vicinity to Pd particles are exchanged as rapidly as H atoms, adsorbed on Pd. For more remote protons, the interchange of O-H and O-D groups follows first order kinetics, but the rate constant is lower for protons in sodalite cages than for those in supercages; the rates are higher for Pd/HY than for Pd/NaHY. Proton exchange is virtually absent for samples which were reduced at 500 °C for several hours, suggesting that the location of Pd inside zeolite cages is essential and that hydrogen spillover is irrelevant.     

The Q-Cascade Explanation

The physical meaning of a continuous profile cascade, which is frequently used in the study of multicomponent isotope separation and named as the Q-cascade is explained. It is found that the parameter Q for a component at a stage is nothing but the relative increase of the concentration of the component, and is constant at all cascade stages. The Q-cascade is classified as the quasi-ideal cascade playing an importantrole for fast evaluation of the separation cascade parameters for multi-isotope mixture separation.     

热扩散法分离氖同位素级联设计及应用

通过计算设计了热扩散法分离氖(Ne)同位素的工艺参数,并进行了单柱试验;在此基础上设计了Ne同位素分离的热扩散级联装置,应用于^22Ne同位素的分离,得到了^22Ne同位素浓缩的动力学曲线及装置的浓缩曲线、产率曲线。试验结果表明该工艺和技术具有较高的分离Ne同位素的效率。     

稳定性同位素15N在我国农业研究中的应用

对近年来稳定性同位素^15N在农业研究中的应用及所取得的成就进行了综述，并展望了稳定性同位素^15N在农业科学研究方面应用的发展前景。     

同位素在大气环境科学研究中的应用

同位素被广泛用于环境科学研究中.本文主要介绍了C、S、N、Pb和Hg等同位素在大气环境研究方面的应用和发展.     

同位素标记胞嘧啶的合成研究

设计了以正丁醇为溶剂,氰基乙醛缩二乙醇和同位素标记尿素混合回流反应,再在酸作用下进行环化反应制备得到标题化合物。设计的合成路线操作简单、工艺流程短、副产物少,收率可达80%,同位素丰度没有降低。产物经HPLC、IR、MS、1HNMR和13CNMR表征。结果表明,化学纯度99%,同位素丰度98 atom%。     

Cancer Cell Metabolites: Updates on Current Tracing Methods

Cancer is the second leading cause of death-1 in 6 deaths globally is due to cancer. Cancer metabolism is a complex and one of the most actively researched area in cancer biology. Metabolic reprogramming in cancer cells entails activities that involve several enzymes and metabolites to convert nutrient into building blocks that alter energy metabolism to fuel rapid cell division. Metabolic dependencies in cancer generate signature metabolites that have key regulatory roles in tumorigenesis. In this minireview, we highlight recent advances in the popular methods ingrained in biochemistry research such as stable and flux isotope analysis, as well as radioisotope labeling, which are valuable in elucidating cancer metabolites. These methods together with analytical tools such as chromatography, nuclear magnetic resonance spectroscopy and mass spectrometry have helped to bring about exploratory work in understanding the role of important as well as obscure metabolites in cancer cells. Information obtained from these analyses significantly contribute in the diagnosis and prognosis of tumors leading to potential therapeutic targets for cancer therapy.     

除草剂的同位素残留分析进展

除草剂的使用对清除农田杂草、提高作物产量、解决粮食问题具有重要意义．但是除草剂的残留会对生态环境和人类健康造成影响。农药的同位素残留分析技术日益受到人们的重视。并取得了长足的发展。本文综述了利用同位素示踪技术对除草剂的残留分析进展。     

激光分离同位素法概述

介绍激光分离同位素的基本情况、基本方法及技术发展的基本条件。     

Linear birefringence in ferroelectric glycine phosphite and deuterated glycine phosphite

Linear birefringence changes were measured with the rotating analyzer method for the glycine phosphite crystal and its deuterated analogue in the vicinity of ferroelectric phase transition. Continuous character of the phase transition was assured. Power rule was found as fulfilled only in close vicinity of T_c. Evident isotope effect was denoted: deuteration changes Tc from 225 to 324K.