表面增强拉曼光谱内标法测定水杨酸浓度

采用电化学方法处理银电极表面,使之产生具有表面增强拉曼光谱(SERS)的活化效应,进而利用水杨酸(SA)吸附于粗糙活化的银电极表面所产生的SERS光谱,进行SA含量的测定。选择硫氰化钾(KSCN)为内标物,以SA的苯环呼吸振动峰(1 036 cm-1)与SCN-的特征峰(2 120 cm-1)强度比值作为相对强度,其相对强度与水杨酸的浓度在4×10-6~3×10-4mol/L范围内呈良好的线性关系,其线性系数为0.993 1;检出限为2.04×10-6mol/L;加标回收率为85.4%~114.6%。方法具有测定简便、内标物干扰小、绿色无害等特点,可进一步推广于其他特殊物质的测定。     

银(Ⅲ)配合物-鲁米诺体系流动注射法测定醋酸泼尼松

在碱性环境下,银(Ⅲ)配合物可与鲁米诺产生化学发光,醋酸泼尼松对该发光体系具有显著的增敏作用,据此提出了流动注射银(Ⅲ)配合物-鲁米诺化学发光体系测定醋酸泼尼松含量的方法。优化的试验条件如下:1鲁米诺溶液中氢氧化钠的浓度为0.6mol·L-1;2鲁米诺溶液的浓度为8.0×10-7 mol·L-1;3银(Ⅲ)配合物溶液中氢氧化钠的浓度为1.7mol·L-1;4银(Ⅲ)配合物溶液的浓度为5.0×10-5 mol·L-1。醋酸泼尼松的线性范围为6.0×10-8~8.0×10-5 mol·L-1,方法的检出限(3s/k)为2.9×10-9 mol·L-1。对1.0×10-6 mol·L-1醋酸泼尼松标准溶液连续测定11次,测定值的相对标准偏差为2.9%。加标回收率在100%~105%之间。     

Ag(Ⅲ)-鲁米诺化学发光体系对泼尼松龙的测定研究

建立了应用Ag(Ⅲ)配合物-鲁米诺化学发光体系检测泼尼松龙的方法。在碱性介质中,泼尼松龙可以改变Ag(Ⅲ)配合物-鲁米诺化学发光体系的光信号,一定范围内,其浓度与光信号的减弱程度呈线性关系。于最优条件下,该方法的线性范围是2.0×10-9~1.0×10-7mol·L-1和2.0×10-7~1.0×10-6mol·L-1,检出限为5.0×10-10mol·L-1。对2.0×10-8mol·L-1与6.0×10-7mol·L-1的泼尼松龙进行平行测定11次,其相对标准偏差分别为1.1%与1.5%。该方法用于醋酸泼尼松龙注射液的测定,回收率为98.0%~101%。本方法具有快速、简便、准确的特点,适用于泼尼松龙新剂型药代动力学的研究,也可应用于泼尼松龙其他剂型的检测。     

荷移反应-紫外分光光度法测定尿酸

本文采用紫外分光光度法研究了尿酸与四氰乙烯之间的荷移反应。尿酸与四氰乙烯可以形成淡绿色的荷移配合物,其配合比为1∶2。在测定波长395 nm处,该配合物的表观摩尔吸光系数ε=6.24×104L.mol-1.cm-1,方法线性范围为5.7×10-7~5.7×10-6mol.L-1。应用本法测定了人体代谢物中尿酸的含量,回收率为96.4%~110.5%,相对标准偏差(RSD)为1.98%(n=7)。     

L-半胱胺尾式卟啉铜(Ⅱ)修饰金电极检测苯酚

将制备的L-半胱胺卟啉铜(Ⅱ) (CuL) 配合物自组装在Au电极表面,获得电化学苯酚传感器(CuL/Au).在pH 7.0的磷酸盐缓冲液(PBS)中于-0.4 V～0.5 V (vs. SCE)电位范围内有一对氧化还原峰,峰电位分别为Epa = 0.09 V和Epc = - 0.06 V.实验结果表明CuL能够催化氧化苯酚,通过产物在电位0.1 V下的电化学响应对苯酚进行测定.该电极对苯酚表现出快速的响应(响应时间＜10 s).传感器对苯酚的测定具有较宽的线性范围(5.0×10-7 mol·L-1～2.5×10-4 mol·L-1),检出限为2.0×10-7 mol·L-1.该电极用于地表水中苯酚含量检测,并与标准方法4-氨基安替比林分光光度法作了对照,结果满意.     

流动注射化学发光法测定蛋白质

采用流动注射化学发光法(FI-CL)研究了鲁米诺-铁氰化钾-蛋白质化学发光反应.试验发现某些蛋白质对鲁米诺-铁氰化钾发光体系有增强作用,对流速、发光试剂浓度、pH值以及增敏剂等条件进行了试验和优化并建立了测定蛋白质的FI-CL方法.测得卵清白蛋白(OVA)、牛血清蛋白(BSA)线性范围分别为1.8×10-10～2.2×10-7mol·L-1(r=0.9964)和1.5×10-10～3.8×10-7mol.L-1(r=0.9988),检出限(S/N=3)分别为1.8×10-10mol·L-1和1.5×10-10 mol·L-1;对7.6×10-8mol·L-1牛血清蛋白标准的相对标准偏差为0.88%(n=6).用于人体血清样品总蛋白的测定,与双缩脲法的结果间无显著差异.     

壳聚糖固定双酶的丝网印刷胆固醇传感器的制备及应用

以亚甲基蓝为电子媒介,通过壳聚糖固定胆固醇氧化酶和辣根过氧化酶在丝网印刷电极表面,制成了一种新型胆固醇生物传感器,实现了低电位下对胆固醇的间接测定.循环伏安法和恒电位法用于研究修饰电极的电化学特性,在优化的试验条件下,安培法对胆固醇响应的线性范围为2.0×10-5～3.0×10-3mol·L-1,检出限(3S/N)为5.0×10-6mol·L-1.用同一支电极对6.0×10-4mol·L-1胆固醇溶液进行10次连续测定,测定值的相对标准偏差为4.6%,用3支电极做相同试验,测得相对标准偏差为6.2%.应用此传感器测定了血清样品中胆固醇含量,测定值的相对标准偏差(n=5)以及回收率试验结果依次在2.3%～6.1%之间及94.3%～105.2%之间.     

掺杂硒修饰碳糊电极伏安法测定对乙酰氨基酚

采用循环伏安法制备了掺杂硒修饰碳糊电极,用循环伏安法和差分脉冲伏安法研究了对乙酰氨基酚在掺杂硒修饰碳糊电极上的电化学行为,建立了掺杂硒修饰碳糊电极测定对乙酰氨基酚的电化学方法。在pH 4.6的0.1mol·L-1乙酸-乙酸钠缓冲溶液中,对乙酰氨基酚在+0.61V呈现一个灵敏的氧化峰。对乙酰氨基酚的浓度在6.0×10-7~1.5×10-4 mol·L-1范围内与其氧化峰电流呈线性关系,检出限(3s/k)为2.8×10-7 mol·L-1。方法用于药品中对乙酰氨基酚的测定,测定结果与药典法测定值相符,测定值的相对标准偏差(n=5)在2.1%~2.5%之间。     

表面增强拉曼光谱法测定牛奶中青霉素G钠的残留量北大核心CSCD

青霉素G钠(NaBP)溶液的常规拉曼光谱信号微弱.将制备的浓缩银纳米粒子(AgNPs)20μL与不同浓度(1×10^(-9)~1×10^(-1)mol·L^(-1))的青霉素G钠溶液(pH 6)20μL混合,所得混合液的表面增强拉曼光谱(SERS)信号显著增强,在上述混合液中加入1×10^(-2)mol􀅰L^(-1)硫酸镁溶液8μL,青霉素G钠SERS增强效果最佳.据此,提出了以AgNPs为基底,硫酸镁为凝聚剂,采用SERS测定青霉素G钠含量的方法,并用于加标牛奶样品的检测.结果表明,青霉素G钠浓度为1×10^(-8)~1×10^(-3)mol·L^(-1)时,其浓度的对数值与相应的SERS信号强度呈线性关系,检出限(3s/k)为8.2×10^(-9)mol·L^(-1).按标准加入法进行回收试验,回收率为80.0%~96.0%,测定值的相对标准偏差(n=5)为2.3%~6.5%.     

一种新型三角架罗丹明B荧光探针对Cu~(2+)识别性能研究

设计、合成了一种新颖的三角架结构罗丹明B衍生物(2).在乙醇-水(8/1,V/V)介质中,用Tris-HCl控制体系pH为6.8,观察到Cu2+对化合物2的荧光及紫外-可见吸收增强性能,同时化合物2对Cu2+具有较高的选择性响应.选择最大激发和发射波长为557/577nm,测定了探针2(1.00×10-5mol·L-1)对Cu2+响应的校准曲线,线性范围为0.10~10.00×10-5mol·L-1,相关系数R2=0.9964(n=15),检出限为1.129×10-7mol·L-1,平行测定5次的相对标准偏差(R.S.D.)为2.2%;以557nm为最大吸收波长测定紫外吸收,Cu2+响应的浓度线性范围为0.50~25.00×10-5mol·L-1,相关系数R2=0.9948(n=13),检出限为3.338×10-7mol·L-1.     

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.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

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.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

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.     

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.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

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.