首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
本文研究了吡啶-2,6-二羧酸体系荧光法同时测定钐、铕、铽、镝的最佳条件及共存离子的影响。其检测限分别为3.0、0.15、0.09和0.5mg/mL。本文采用荧光法与阳离子交换树脂分离法联用,同时测定了地质和环境试样中的杉、铕、铽、镝含量。  相似文献   

2.
本文探讨了苹果酸、酒石乳、苯基乳酸和乳酸等α-羟基羧酸类络合体系荧光法测定铽、镝。发现上述配体均能使铽的荧光增敏,苯基乳酸还能使镝的荧光增敏,并成功地测定了几种稀土氧化物中 Tb_4O_7含量。  相似文献   

3.
本研究了吡啶-2,6-二羧酸(DPA)体系导数荧光法同时测定铀,钐,铕,铽,镝的最佳条件。在pH5.5,4.8×10^-^5mol/LDPA,激发波长272nm的条件下,可分别在518,639,621,539和66nm处测定铀,钐,铕,铽和镝,检测限分别达到7,0.4,0.004,0.026和0.25ng/mL。应用本法测定了混合成试液中上术五种离子含量,回收率为92.3-108.1%。  相似文献   

4.
在铽镝钬分离工艺中,要求控制镝(80—90%)钬(10—20%)混合物中铽<0.03%(均以氧化物计),而发射光谱法测定镝基体中铽的下限为0.07%。H.C.Полуэктов曾研究用钛铁试剂萤光光度法测定铽,我们在前人工作的基础上,进一步进行了试验。表明,铽-钛铁试剂络合物的萤光具有较高的灵敏度,但共存的镝钬及其他稀土元素和常见元素的含量变化,对铽的萤光强度有一定影响。为消除基体组份变化及可能存在的其他离子影响,需采用标准加入法。铽络合物在24小时内萤光强度不变,但其萤光强度受紫外光  相似文献   

5.
本文研究了TbCl_3-DyCl_3-HCl-H_2O-P507体系的萃取平衡关系,关联了分配比模型:(1)以水相中稀土总浓度的分区模型;(2)以摩尔分数的分区模型;(3)铽和镝的模型。利用上述模型研究了铽镝二元体系的萃取行为,其与单一铽或镝相比,由于第二元素的存在导至了分配比、分离因数和有机相的稀土浓度的变化。利用水相稀土浓度的分区模型,进行了分馏萃取静态特性模拟。探索了影响分离工艺的因素、研究了萃取因数与分离效率的关系和在实际中达到材料消耗低和分离效率高的最优条件。提出了达到铽>95%和镝>99.5%的最优分离工艺。  相似文献   

6.
铽-亚氨基二乙酸-钛铁试剂休系,镝-氨羧络合剂-钛铁试剂体系已有研究报道。铽和镝是稀土元素中原子序数相邻的两个元素,两者共存,不易分离分别测定,基于此,本文研究了在亚氨基二乙酸-钛铁试剂-表面活性剂(CTMAB)体系中荧光光度法同时测定铽和镝。操作步骤:于25ml比色管中加入Tb~(3+)和Dy~(3+)的混合液,然后依次加入亚氨基二乙酸(1×10~(-3)mol/L),钛铁试剂(1.0×10~(-4)mol/L),乙二胺缓冲溶液(pH12)各1.0ml,表面活性剂(3×10~(-2)mol/L)3.0ml,  相似文献   

7.
提出了以Tb(Dy,Sin)-Gd-BPMPHD-CTMAB共发光体系同时测定铽,镝和钐的方法.测定的线性范围为铽1.0×10~(-10)~1.O×10~(-6)mol·L~(-1),镝1.O×10~(-7)~1.3×10~(-5)mol·L~(-1),钐1.O×10~(-7)~8.0×10~(-6)mol·L~(-1).  相似文献   

8.
高纯氧化铽中铕、钆,镝、钬和钇的ICP光谱测定   总被引:1,自引:0,他引:1  
本文提出了用ICP-AES法直接测定高纯氧化铽中微量稀土杂质铕、钆、镝、钬和钇的新方法。实验中,在样品溶液里加入70%(V/V)的乙醇,增加了谱线强度,降低了背景,进一步提高了灵敏度。本方法可用于>99.99%的高纯氧化铽的分析方法准确、灵敏、简便而且快速。当溶液样品浓度为5mg/ml时,高纯氧化铽中5个稀土杂质的测定下限的总量为70PPm.用人工合成样品做准确度实验结果是令人满意的。其相对标准偏差为1.8—3.0%。  相似文献   

9.
研究了铽—间苯二甲酸—TOPO—Triton X—100体系的荧光特性,在体系的最大激发波长(283nm)和最大发射波长(545nm)下,分别确定了间苯二甲酸、TOPO、Triton X—100的最佳浓度和体系的最佳pH。协同配体TOPO和非离子表面活性剂Triton X—100的引入,使体系的荧光强度较铽—间苯二甲酸二元体系提高约210倍。在最佳条件下,铽离子浓度在1.0×10~(-8)~6.0×10~(-7)ml·L~(-1)范围内与体系的荧光强度成线性关系,检出限为1.0×10~(-9)ml·L~(-1),此体系用于测定混合稀土样品中痕量铽,结果满意。  相似文献   

10.
激光-液体荧光法研究——Ⅰ.稀土元素铽、镝和钐的测定   总被引:4,自引:1,他引:3  
在液体荧光法中用激光作激发光源大大提高了检测有机物和无机物的灵敏度。Полуэктов等在以汞灯为激发光源用钛铁试剂为铽的荧光试剂的液体荧光法中,测铽的检测限为4ppt。在同样条件下,他们也观察到了镝和钐的荧光,但由于其强度太弱,不能用于实际分析。在该法中,钛铁试剂与铽形成的二元络合物在紫外光连续照射下,其荧光强度逐渐下降,给测量带来不利影响。本工作同样采用钛铁试剂为荧光试剂,以氮分子激光  相似文献   

11.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

12.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

13.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

14.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

15.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.  相似文献   

16.
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.  相似文献   

17.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion.  相似文献   

18.
19.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

20.
Quercetin, the polyphenolic compound, which has the highest daily intake, is well known for its protective effects against aging diseases and has received a lot of attention for this reason. Both quercetin 3-O-β-d-glucuronide and quercetin 3′-O-β-d-glucuronide are human metabolites, which, together with their regioisomers, are required for biological as well as physical chemistry studies. We present here a novel synthetic route based on the sequential and selective protections of the hydroxyl functions of quercetin allowing selective glycosylation, followed by TEMPO-mediated oxidation to the glucuronide. This methodology enabled us to synthesize the five O-β-d-glucosides and four O-β-d-glucuronides of quercetin, including the major human metabolite, quercetin 3-O-β-d-glucuronide.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号