水溶性苯胺蓝光度法测定蛋白质

在pH1．0～2．3的酸性介质中,水溶性苯胺蓝与牛血清蛋白、人血清蛋白、卵白蛋白、α-糜蛋白酶作用形成结合产物时将导致溶液光吸收发生变化,在558nm褪色,在634nm附近吸光度增强,且吸光度差(△A)值均与蛋白浓度成正比,不同蛋白质分别在0～50mg／L或20～80mg／L范围内符合比耳定律。据此,建立了一种新的光度测定蛋白质的新方法。它用于人血清和尿液样品中总蛋白质的质量测定,回收率在95％～102％之间,结果满意。     

双波长分光光度法测定牛奶中的钙

采用双波长分光光度法测定牛奶中钙离子的含量。基于在碱性缓冲液中,钙与铬黑T（EBT）-聚乙二醇溶液作用形成1：1的配合物,利用等吸收双波长消去法,消除EBT自身的干扰。在558mn和645m处测定,得吸光度差△A,钙的质量浓度在0-4．8μg／mL范围内符合比耳定律,线性回归方程为△A=0．06964c＋0．00986,产0．9989。用干灰化法处理样品,通过测定样品的△4,查得样品中钙离子的含量。该方法测定结果的相对标准偏差为1．7％～7．6％（n=5）．平均加标回收率为79．0％～98．7％。     

石墨炉原子吸收法测定合金钢中痕量砷的干扰抑制

研究了石墨炉原子吸收法测定合金钢中痕量砷的实验条件和干扰抑制方法。在合金钢样品溶液中加入硝酸镍溶液作基体改进剂,不仅提高了砷的灰化温度,而且提高了测定灵敏度。砷的含量与吸光度呈良好的线性关系,线性相关系数r=0．9846。测定结果的相对标准偏差小于6．5％,加标回收率为95％～106％。检出限为0．01ug／mL。     

高锰酸根褪色光度法测定食盐中的微量碘离子

在稀硫酸介质中，碘离子能快速、定量地还原高锰酸根，在加入碘离子前后，高锰酸钾溶液在波长525nm处的吸光度发生显著变化，且吸光度之差ΔA与加入的碘离子的浓度成正比，确定了最佳反应条件，建立了高锰酸根褪色光度法测定食盐中微量碘离子的新方法。方法的线性范围为0-20μg／mL，线性回归方程为ΔA=0．0165c 0．0041，相关系数r=0．9987，检出限为0．17μg／mL。用于食盐中微量碘离子的测定，加标回收率为91．0％～95．0％．相对标准偏差为0．35％～0．75％。     

亚硝基铁氰化钠分光光度法测定药品“必理通”中对乙酰氨基酚含量

用亚硝基铁氰化钠分光光度法测定药品“必理通”中的对乙酰氨基酚含量。采用亚硝基铁氰化钠试液为显色剂,蒸馏水做溶剂,在波长为700nm下有最大吸收,利用分光光度计测定不同浓度溶液的吸光度,并绘制标准曲线进行分析。实验证明,对乙酰氨基酚在0．024mg／mL～0．168mg／mL浓度范围内,吸光度与样品浓度的线性关系良好,回收率在98．0％以上。此测定方法准确、快速、简便,是测定对乙酰氨基酚含量的最佳方法之一。     

烟酸直接电氧化合成反应液的全分析

将非水溶液电位滴定法和紫外分光光度法相结合,对3-甲基吡啶(3-MP)直接电氧化合成烟酸反应液中烟酸、H2SO4、3-MP进行了全分析。以二甲基甲酰胺(DMF)作溶剂进行非水溶液电位滴定,可准确测定烟酸和H2SO4的含量,测定结果的相对标准偏差分别为2．08％和0．908％;平均回收率分别为101％和99．9％。在262nm波长下进行紫外检测,烟酸和3-MP在H2SO4水溶液中吸光度具有良好的加和性,烟酸、3-MP的浓度在0．0610～0．122mmol／L范围内与吸光度呈很好的直线关系,方法的相对标准偏差为3．52％,平均回收率为99．9％。     

离子色谱法测定地下水中的乙酸根含量

对地下水样品除氯后，选用1．35mmol／LNa2CO3-1．00mmol／LNaHCO3混合溶液作淋洗液，用离子色谱法测定地下水样品中乙酸根的含量，乙酸根浓度在0～5．00mg／L范围内与电导率峰高呈线性关系，线性回归方程为H=15950．6c-442．7，相关系数为0．9994，方法的检出限为0．05mg／L，加标回收率为101％-110％，测定结果的相对标准偏差为2．3％。     

双波长分光光度法测定阿丙沙星可溶性粉中阿莫西林、盐酸环丙沙星的含量

应用双波长分光光度法测定阿丙沙星可溶性粉中阿莫西林、盐酸环丙沙星的含量。以pH=5．0的磷酸盐缓冲液为溶剂,在波长229、248、315、400nm处进行测定,阿莫西林的浓度在5．130～25．650μg／mL、盐酸环丙沙星的浓度在4．888～24．440μg／mL范围内分别与其吸光度差值呈良好的线性关系。阿莫西林的回收率为99．30％～100．19％,测定结果的相对标准偏差为0．60％～1．00％(n=5),盐酸环丙沙星的回收率为99．30％～99．86％,测定结果的相对标准偏差为0．84％～1．02％(n=5)。     

磷酸三丁酯萃取火焰原子吸收法间接测定植物和煤灰中的痕量锗

本文报道了磷酸三丁酯萃取-火焰原子吸收法间接测定植物及煤灰样品中痕量锗的新方法。锗与钼酸铵在0．3mol／L的硝酸介质中形成稳定的锗钼杂多酸,被磷酸三丁酯萃取,有机相直接进样测定钼而间接测定锗;特征浓度为21．8ng／mL／1％吸光度,RSD(n=11)为4．6％,加标回收率为97．6％～101．2％。     

2,3,7-三羟基-9-水杨基荧光酮催化动力学光度法测定痕量Ni(Ⅱ)

基于在NaOH溶液中及45℃加热条件下,Ni(Ⅱ)对H2O2氧化2,3,7-三羟基-水杨基荧光酮溶液褪色反应具有灵敏的催化作用.研究了反应的最佳条件,建立了催化动力学光度法测定痕量Ni(Ⅱ)的光度分析方法.非催化反应与催化反应的吸光度差值△A与Ni(Ⅱ)的质量浓度P在0.00～0.15μg/mL范围内呈良好的线性关系,...     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

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%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.