气相色谱-质谱联用测定氘标记卤代苯及其衍生物的同位素丰度

稳定同位素氘标记卤代苯及其衍生物是一类重要的氘标记基础试剂。以溴苯-D5为例,开发了基于气质联用的氘标记卤代苯及其衍生物同位素丰度表征方法,考查了样品配制溶剂和配制浓度对同位素丰度值的影响,在优化的测试条件下,所发展的方法具有良好精密度和准确度。最后,对上海化工研究院研制的氘标记实际样品溴苯-D5、4-硝基溴苯-D4和4,4'-二硝基二苯硫醚-D8的同位素丰度进行了测定,分别为99.6 atom%、99.5 atom%和99.1 atom%。该方法能够快速、准确、高效地测定氘标记卤代苯及其衍生物的同位素丰度。     

重氢重氧水制备重氧水，副产重水的方法研究

以重氢重氧水(D:35.1 atom%;~(18)O:97.2 atom%)为同位素原料,先通过氢氧气发生器获得D_2和~(18)O2,再将D_2、~(18)O_2分别通入石英管在催化剂催化作用下与过量高纯氧气/高纯氢气反应,合成得到35.1 atom%重水和97.2 atom%重氧水。结果表明,该方法具有同位素丰度稀释少,易调节的优点,可以作为水精馏法生产重氧水的后处理工艺,并可以副产一定丰度重水。     

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%。     

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。     

稳定同位素标记莨菪亭-2-~(13)C的合成

以2,4,5-三甲氧基苯甲醛和乙酰氯-2-13C为原料,经3步反应合成目标化合物。以原料乙酰氯-2-13C计算,目标化合物总收率为26%,产品经LC-MS、1HNMR、13CNMR、IR检测,化学纯度99%,13C同位素丰度为98.5 atom%。     

氘代氨基甲酸酯类化合物的合成与表征

设计了以有机酚为原料制备氘代氨基甲酸酯类化合物的合成路线。有机酚(Ⅰa~Ⅰc)在Na OH催化作用下,经与三光气(BTC)反应,合成了中间体氯甲酸酯(Ⅱa~Ⅱc),再与一甲胺-D3-盐酸盐缩合反应,制得目标化合物(Ⅲa'~Ⅲc')。设计的合成路线避免使用异氰酸酯,且操作简单,工艺流程短,副产物少,收率可达60%以上,氘同位素丰度没有降低。产物经HPLC、MS、1HNMR和13CNMR表征,结果表明,化学纯度99%,氘同位素丰度99 atom%。     

基于酶催化反应测定15N标记尿素同位素丰度

基于酶催化反应建立¹⁵N标记尿素同位素丰度的测定方法。10 mg ¹⁵N标记尿素先在50 mg脲酶溶液中催化生成¹⁵N标记碳酸铵,然后在碱性、65℃下分解产生¹⁵N标记氨气并用酸吸收后生成¹⁵N标记铵盐,¹⁵N标记铵盐与次溴酸钠反应生成¹⁵N标记氮气,再将生成的¹⁵N标记气体引入MAT-271型气体同位素质谱仪中检测相对原子质量为28、29和30的离子流强度,根据不同丰度范围计算¹⁵N同位素丰度。结果表明：针对低、中、高不同¹⁵N同位素丰度的尿素样品,采用脲酶催化法测定的¹⁵N丰度与微量高温燃烧法的偏差均小于0.2%,相对标准偏差均小于0.3%,适用的¹⁵N同位素丰度范围为0.365%～99.2%。脲酶催化法准确度较高,精密度良好,适用于¹⁵N标记尿素同位素丰度的检测。     

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。     

稳定同位素~(15)N标记2-甲基-5-硝基咪唑的合成与表征

以15NH3和H15NO3作为同位素原料,经两步反应得到目标产物15N标记2-甲基-5-硝基咪唑。收率以15NH3计,为58%,经液相色谱(HPLC)、质谱(MS)、气体同位素质谱计(MAT-271)等对其纯度和丰度进行表征,纯度99.5%,丰度99%,可作为制备15N标记硝基咪唑类药物内标检测试剂的合成前体。     

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。     

Enrichment of 41K isotope in potassium formed on and in a rhenium electrode during plasma electrolysis in K2CO3/H2O and K2CO3/D2O solutions

It was found that potassium forms on rhenium electrodes during plasma electrolysis in K₂CO₃/H₂O and K₂CO₃/D₂O solutions, and the new potassium has unnatural isotopic ratios. The isotope ⁴¹K increases from the natural abundance, 6.7%, to as much as 32–37%. The percentage of ⁴¹K in the potassium contamination in a rhenium electrode before electrolysis was close to the natural isotopic abundance (6.7%). This result suggests that the ⁴¹K was enriched by some unknown process connected with a vigorous discharge of plasma electrolysis.     

Vanadium of petroleum asphaltenes and source kerogens (La Luna Formation, Venezuela): isotopic study and origin

High-resolution mass spectrometry indicates that the isotopic abundance of ⁵⁰vanadium (V) of the Late Cretaceous La Luna petroleum asphaltenes and related source kerogens of marine origin (both highly enriched with V>2000 ppm) is higher by about 3.5% than that of inorganic source (VOSO₄·5H₂O, Merck). Similar results are obtained with the isotopic analysis of the asphaltenes (containing high V) extracted from the floating asphalts (Dead Sea, Israel). We propose that the difference in the ⁵⁰V/⁵¹V values between the La Luna petroleum asphaltenes/source kerogens and inorganic source can be best ascribed to the biological processing of the seawater V. The fact that the isotopic composition of V of the vary over a very narrow range (2.46-2.52) suggests an essentially same (or similar) and fixed (micro)biological source of V. Isotopic analysis was also extended to the methanol-soluble fractions of the La Luna asphaltic petroleums (DM-119/-120/-124) highly enriched with extractable (alkyl) vanadyl-porphyrins (VO²⁺-P). This analysis shows that the isotopic abundance of ⁵⁰V for the methanol-soluble fractions agrees (within the limits of experimental error) with those of the asphaltenes/kerogens.     

Isotope Separation of Nitrogen by Ion Exchange Chromatography in a Cascade System

The ion exchange chromatography technique in a cascade process was used to separate stable isotopes of nitrogen (¹⁴N/¹⁵N). For this purpose, three column systems (with different internal diameters, S1?14.5 cm; S2–9.5 cm; S3–5.2 cm) were used that contained the cationic resins DOWEX 50 WX8 (as H⁺ and equilibrated with H₂O) and measured 1.7 m in height. Isotopic fractionation of nitrogen occurs during displacement band chromatography (DBC) of the NH₃ (aq) solution with a 0.75 mol L^?1 NaOH solution. The active sites of the resin were previously saturated to form NH₄ ⁺ (RNH₄) with a 0.75 mol L^?1 solution of (NH₄)₂SO₄ at a natural isotopic abundance (0.366 at. %) in ¹⁵N. The NH₄ ⁺/NH₃ (aq) equilibrium was determined during the DBC, which enriched the rear portion of the band with ¹⁵N. In S1, enrichment of approximately 5 at. % of ¹⁵N in the last 10 cm was achieved. After four interactions (couplings) between S1–S2, an enrichment of approximately 50 at. % of ¹⁵N was obtained. During the interaction between S2–S3, after the second coupling, an isotopic enrichment of approximately 90 at. % of ¹⁵N was observed, which produced 70 g month^?1 of (¹⁵NH₄)₂SO₄.     

稳定同位素标记D6-氯丙那林的合成

D6-氯丙那林的合成以邻氯苯乙酮和D6-丙酮为起始原料，邻氯苯乙酮与溴化铜通过溴化反应得到α-溴代邻氯苯乙酮，D6-丙酮经过还原、溴化、胺化、肼解、碱解得到D6-异丙胺，然后α-溴代邻氯苯乙酮和D6-异丙胺通过胺化、还原“一步法”合成得到稳定同位素标记的D6-氯丙那林，以投入的D6-异丙胺的物质的量计算产率为26.2%。目标产物结构经NMR、MS、HPLC和X-ray单晶衍射等表征确认，液相色谱纯度大于98%，液质丰度99.7% atom D，可作为内标试剂用于氯丙那林残留的检测。     

化学-酶法制备^15N-L-酪氨酸的研究

通过化学-酶法途径制备了稳定性同位素标记的^15N-L-酪氨酸。以大肠杆菌所含的天冬氨酸转氨酶催化自制的对羟基苯丙酮酸和^15N-L-天冬氨酸,转化成^15N-L-酪氨酸。主要对酶转化的条件进行了研究,酶反应液经分离纯化后,得到的^15N-L-酪氨酸产品的丰度达98．62％,比原料下降了0．44％,^15N的利用率达40．78％。     

MFC-好氧颗粒污泥系统中C/N对阴极微生物的影响

为了探索微生物燃料电池更广泛的适用性，本试验将好氧颗粒污泥（AGS）与微生物燃料电池（MFC）进行耦合，并采用序批式运行方式，固定进水COD为780 mg/L，通过改变NH4+的浓度（39、50、78和156 mg/L）将碳氮比（C/N）分别调节为5、10、15、20，研究了不同C/N对系统阴极室内微生物的多样性和群落结构产生的影响。通过高通量测序分析显示，随着进水C/N的变化，阴极室内不同菌群的相对丰度都产生了明显的变化。在门水平下，最为丰富的变形菌门（Proteobacteria）的相对丰度在C/N=10时，占比为45%；而在C/N=20时，降为41.1%。在纲水平下，相对丰度变化幅度最大的异常球菌纲（Deinococci）在C/N=5时占比最大达到27.2%，在C/N=20时占比最小只有15.1%。在C/N=15和20的条件下，阴极室内微生物的新陈代谢相对丰度最高，为77.1%，对应的阴极好氧颗粒污泥代谢较强，这对微生物降解COD有着举足轻重的作用。     

Unexpected enrichment of nitrogen during the diagenetic evolution of sedimentary organic matter

This study examines the behaviour of nitrogen during coalification in two coal series: the sedimentologically homogeneous coal series of the Mahakam delta, Indonesia and a reference coal series composed of samplesfrom several sources. The variations in the total nitrogen contents, in hydrolysable nitrogen, and in the natural isotopic abundance of ¹⁵N are reported. The behaviour of nitrogen during coalification presents three main stages: 1. a first stage where microbial and/or chemical degradations produce a loss of nitrogen; 2. a second stage of preservation, where organic nitrogen does not take part in the reactions involved and consequently remains unchanged in the residual organic matter; and 3. a third stage of thermal alteration, where nitrogen is mainly released with methane.     

15N-labelled urea recovery by different crops in the Sudan Gezira soil

The aim of this work was to provide practical information on the efficient utilization of urea-nitrogen by wheat, cotton and sorghum using¹⁵N isotopic tracer method. The utilization efficiency of applied nitrogen was found to be dependent on the crop ability to remove nitrogen from the soil solution over a relatively short period. Mixing 42 kg P per ha with 84 kg N increased wheat grain yield by about 30%, and N recovery by about 50% over the same N treatment without P. Placement of urea 10–20 cm deep increased %Ndff by cotton over surface-application by about 45% and the % N recovery by about 55%. N recovery by sorghum was low, and was improved slightly by application of urea four weeks after sowing compared to application at sowing. Loss of N as NH₃ from surface applied urea was presumably the major avenue of loss which reduced N recovery by the different crops, especially sorghum and cotton. Urea-N recoveries calculated by the difference method and the¹⁵N isotopic method show the more reliability of the latter method.     

稳定性同位素氘标记对羟基苯甲酸正丁酯的合成与表征

以对羟基苯甲酸-环-D4为同位素原料,酸性条件下与正丁醇反应得到对羟基苯甲酸正丁酯-环-D4。考察了酸性催化剂种类对产物同位素丰度的影响,筛选出最佳酸性催化剂对甲苯磺酸。通过单因素实验得到优化后的工艺参数,n(正丁醇)∶n(对羟基苯甲酸-环-D_4)=5∶1,m(对甲苯磺酸)∶m(对羟基苯甲酸-环-D_4)=0.05∶1,反应温度为95℃,反应时间为4.5 h。产物经GC-MS、~1HNMR和FT-IR进行分析,化学纯度99.0%,同位素丰度97 atom%D。