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1.
提出了比值导数波谱-多波长最小一乘回归分光光度法。该法能同时测定三组分混合物而毋需零交点波长和等吸收点,且回归稳健性好.可消除异常点的影响。方法用于合成样品和饮料中糖精钠、苯甲酸和山梨酸的同时测定,相对误差<± 3. 5%,回收率为 96. 6%~104.4%,相对标准偏差为2.0%~3.1%.  相似文献   

2.
将双波长K系分光光度法和多波长线性回归分光光度法相结合,并采用最小一乘法准则计算回归系数,提出了一种同时测定三组分的新方法,即K系数-多波长最小一乘回归分光光度法。  相似文献   

3.
硫化物的快速分光光度法测定   总被引:8,自引:0,他引:8  
黄兰芳  汪炳武 《分析化学》1997,25(10):1192-1194
提出了测定微量硫化物的快速亚甲蓝分光光度法,实验结果表明,在硫酸溶液中,K2Cr2O7+对二甲氨基苯胺+S^-2迅速显色反应形成亚甲蓝,表现摩尔吸收系数为4.06×10^4L.mol^-1.cm^-1;最大吸收波长为664nm;线性范围为0~0.8mg/L,实验了采用全差示光度法直接测定水中硫化物的条件,用于某江水中21.6μg/L硫化物测定时,相对标准偏差为3.2%(n=6);试样的标准加入回收  相似文献   

4.
本文将导数分光光度法与多波长线性回归法联用,测定了电有机合成产品中的对苯二酚、邻苯二酚和苯酚的含量。回收率在95.0%~100.1%之间。模拟合成样品分析结果的相对误差为0.1%~6.6%。方法简便。  相似文献   

5.
本文将导数分光光度法与多波长线性回归法联用,测定了电有机合成产品中的对苯二酚,邻苯二酚和苯酚的含量,回收率在95.0%~100.1%之间,模拟合成样品分析结果的相对误差对0.1%~6.6%。方法简便。  相似文献   

6.
本文提出了用二苄基二硫代乙二酰胺(DbDO)为显色剂分光光度测定铑的方法,并进一步研究了该试剂与钯、铂的反应,从而建立了可在一个试样中同时测定该三元素的方法。在2~3mol/LHC1溶液中,钯与DbDO在室温显色,用氯仿萃取并用8.4mol/LHC1振荡有机相,然后在454nm测定。在萃余液中加入SnCl_2,并在沸水浴中加热,使铂、铑的DbDO络合物生成,再用氯仿萃取,8.4mol/LHC1振荡有机相,以双波长分光光度法同时测定。其中铂用双波长系数倍率法(λ′_2=521nm,λ′_1=500nm,K=2.563),铑用双波长等吸收波长法(λ_2=400nm,λ_1=546nm)。铂和铑的含量为1:5或5:1时互不干扰。  相似文献   

7.
马波  刘立行 《分析化学》1994,22(10):1033-1036
本文提出了一种同时测定多组分的新方法,即等吸收点-多波长线性回归-导数分光光度法。利用金属离子-5-Br-PADAP-CPB三元络合显色体素,同时测定了重油中的铜、镍、锌,相对标准偏差小于2.6%,分析结果与ICP-AES及GF-AAS法吻合。与常规分光光度法比较,灵敏度提高10倍左右。  相似文献   

8.
提出了比值导数光谱多波长最小二乘回归分光光度法测定苯甲酸、苯甲醛和苯甲醇三组分混合物。合成试样4 次平行测定的相对标准偏差为0 .16 % ~4.35 % 。回收率在91 .43 % ~105.9 % 之间。  相似文献   

9.
提出了比值导数光谱-多波长最小二乘回归分光光度法测定苯甲酸、苯甲醛和苯甲醇三组分混合物。合成试样4次平行测定的相对标准偏差为0.16%~4.35%。回收率在91.43%~105.9%之间。  相似文献   

10.
研究了主成分回归和偏最小二乘方法在多组分分光光度法分析中的应用,以5-Br-PADAP(2〔5-溴-2-吡啶)-偶氮〕5-二乙氨基苯酚)为显色剂,OP(聚乙二醇辛基苯基醚)作为增溶增稳剂,在pH=3.6的条件下,用主成分回归及偏最小二乘分光光度法同时测定了合成样中的铜、钴、镍、钒4组分含量,测定相对误差在-6.00%~4.00%之间。实验证明,对于加和性不好的体系偏最小二乘分光光度法要优于主成分回  相似文献   

11.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.  相似文献   

12.
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   

13.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.  相似文献   

14.
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   

15.
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   

16.
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   

17.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.  相似文献   

18.
19.
《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.  相似文献   

20.
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   

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