同步导数荧光光谱法测定食品中3种芳香族氨基酸

提出了同步导数荧光光谱法同时测定食品中色氨酸、酪氨酸和苯丙氨酸的方法。试验表明:为排除干扰,色氨酸、酪氨酸和苯丙氨酸的特征同步导数荧光波长宜选定279,224,256 nm,波长差Δλ为55,70,25 nm条件下进行同步扫描。3种芳香族氨基酸的浓度分别在一定范围内与其导数荧光强度呈线性关系,检出限（3s/k）分别为6.3×10^-9,1.6×10^-8,4.0×10^-7mol·L^-1。方法用于蜂蜜、羊奶粉和啤酒样品中3种芳香族氨基酸的测定,回收率在92.3%～103%之间。     

多壁碳纳米管修饰电极同时测定维生素B2、B6、B12和维生素C

制备了多壁碳纳米管修饰玻碳电极(MWNT/GCE),研究了维生素B2、B6、B12和维生素C共存时在该电极上的电化学行为.实验发现,在HAc-NaAc缓冲溶液中,该电极可同时测定以上四种维生素,线性范围分别为1.0×10-6～1.0×10-4 mol/L、5.0×10-5～2.0×10-3 mol/L、5.0×10-5～7.5×10-4 mol/L和5.0×10-5～2.0×10-3 mol/L,其检出限分别为7.0×10-7 mol/L、1.0×10-5 mol/L、2.5×10-5 mol/L和5.0×10-6 mol/L.样品分析的RSD分别为1.66%、1.71%、2.26%和1.46%.方法简便快捷,可用于四种维生素同时分析测定.     

聚对氨基苯磺酸修饰玻碳电极不可逆双安培法测定酪氨酸

在玻碳电极上成功地制备了聚对氨基苯磺酸修饰电极(P-p-ABSA/GCE),研究了酪氨酸在该修饰电极上的电化学行为.将此修饰电极用于流动注射不可逆双安培体系的构建,建立了流动注射双安培法直接测定酪氨酸的方法.在0 V外加电压下,在0.005 mol/L硫酸载液中,酪氨酸的氧化峰峰电流与其浓度在2.0×10-6 ～2.0×10-4 mol/L范围内呈良好的线性关系,方法的检出限(S/N=3)为1.0×10-7 mol/L.连续测定1.00×10-5 mol/L的酪氨酸标准溶液,电流值的相对标准偏差(RSD)为1.48%(n=20).该方法具有较高的选择性和灵敏度,应用于测定复方氨基酸注射液中酪氨酸的含量的测定,结果比较满意.     

多壁碳纳米管修饰电极用于离子色谱分离电活性氨基酸的安培检测

将经羧基化的多壁碳纳米管(MWNTs)修饰在玻碳电极表面,制得碳纳米管修饰电极,并通过循环伏安法研究了某些可氧化的氨基酸在该电极上的电催化行为。该电极对半胱氨酸,色氨酸和酪氨酸有明显的电催化作用,且具有较高的灵敏度和稳定性。在一定的色谱条件下,经过离子色谱分离,这些可氧化的氨基酸的检测限分别为:半胱氨酸7.0×10-7mol L;色氨酸2.0×10-7mol L;酪氨酸3.5×10-7mol L(3倍信噪比)。方法已用于头发中这些氨基酸含量的测定。     

Ce(Ⅳ)-吐温40-色氨酸化学发光体系的研究与应用

实验观察到在酸性条件下,色氨酸能够增强Ce(Ⅳ)和吐温40的化学发光反应,其发光强度的增加与色氨酸含量在一定的范围内呈线性关系,据此建立了测定色氨酸的化学发光分析新方法.采用顺序注射技术进样,将试样和试剂的消耗降至微升范围内,明显提高了分析速度.考察了各种实验参数的影响和可能的反应机理,此反应的发光体为Tween 40的中间氧化产物.在试样体积70 μL、吐温40浓度为5%、试剂Ce(Ⅳ)体积80 μL、浓度为1.0 mmol/L、检测流速为1.8 mL/min的条件下,线性范围为2.0×10-7～1.4×10-5 mol/L; 检出限(3σ)为8.8×10-8 mol/L; 对6.0×10-6 mol/L色氨酸进行9次测定的相对标准偏差为1.3%.啤酒和血清中色氨酸含量测定的回收率为91.2%～102%.     

乙醇-K2HPO4-KH2PO4双水相萃取固体基质室温燐光法测定色氨酸

提出了一种基于乙醇-电解质-水体系双水相萃取、固体基质室温燐光法(SS-RTP)测定色氨酸的新方法:将适量电解质和乙醇加入试液中,离心后用SS-RTP测定上相中的色氨酸.在最佳萃取体系乙醇-K2HPO4-KH2PO4-H2O中,测定色氨酸的线性范围1.0×10-7～2.0×10-6mol/L、检出限5.4×10-9mol/L(S/N=3).用于大豆、大米、玉米和竹笋中色氨酸的测定,相对标准偏差2.2%～3.3%,与荧光法比较,相对误差-3.3%～3.2%.     

荧光猝灭法测定磷酰化氨基酸

建立了通过磷酰化氨基酸水解产生无机磷酸盐猝灭铽离子-钛铁试剂络合物(Tb3 -TR)荧光探针的间接荧光法测定三种磷酰化氨基酸。在最佳实验条件下,方法测定磷酰化丝氨酸(P-Ser)、磷酰化苏氨酸(P-Thr)和磷酰化酪氨酸(P-Tyr)的线性范围分别为5.0×10-8~5.0×10-7mol/L、5.0×10-8~6.0×10-7mol/L、5.0×10-8~6.0×10-7mol/L;检出限分别为2.06×10-8mol/L、1.13×10-8mol/L和1.74×10-9mol/L。该方法最后用于卵黄高磷蛋白中含磷量的测定,取得定量结果。     

线扫伏安法同时测定5-羟基色氨酸和色氨酸

研究了色氨酸和5-羟基色氨酸在玻璃碳电极上的电化学行为,研究了不同pH、静置时间、扫描速度以及表面活性剂等的影响,探讨了色氨酸和5-羟基色氨酸在玻璃碳电极上的氧化机理,建立了线扫伏安法同时测定色氨酸和5-羟基色氨酸的方法.实验发现,在含3.33×10-4 mol/L十二烷基磺酸钠的0.1mol/L柠檬酸(pH=4.50)介质中,5-羟基色氨酸和色氨酸分别在 0.675V和 1.070V产生一灵敏的氧化峰.对5-羟基色氨酸,相应的氧化峰的峰高与浓度在2.40×10-5 mol/L～8.00×10-4 mol/L范围内呈良好的线性关系,线性相关系数为0.9994;对色氨酸,其氧化峰的峰高与浓度在2.40×10-5 mol/L～6.40×10-4 mol/L浓度范围内呈良好的线性关系,线性相关系数为0.9929.该方法测量2.00×10-4 mol/L色氨酸和5-羟基色氨酸的相对标准偏差分别为3.2%和3.8%(n=10).     

毛细管电泳脉冲安培检测药物制剂中的氨基酸

基于毛细管电泳三脉冲安培检测技术,同时测定了氨基酸注射液中具有电活性的色氨酸和酪氨酸的含量。研究了三脉冲电位及时间、电解液的浓度、酸度、电泳电压及进样时间对电泳分离和检测的影响,得到了最优测定条件。以铂微盘电极为工作电极,Ag/AgCl为参比电极,三脉冲电位为:E1-900mV,t1100ms;E2700mV,t2100ms;E3950mV,t3100ms,在15mmol/L的磷酸盐(pH=11)缓冲溶液中,上述两组分在10min内完全分离。测定色氨酸和酪氨酸的线性范围分别为1×10-3～5×10-7mol/L和1×10-3～8×10-7mol/L,检出限分别为0.25μmol/L和0.17μmol/L(S/N=3);平行进样的峰电流相对标准偏差(RSD)分别为2.9%和3.3%(n=7)。     

流动注射化学发光法测定3种氟喹诺酮类药物

研究发现,氟喹诺酮类药物对可溶性Mn(-甲醛化学发光体系有强烈的增敏作用,结合流动注射技术,建立了3种氟喹诺酮类药物诺氟沙星、氧氟沙星和环丙沙星的流动注射化学发光新方法。在优化的实验条件下(2×10-4molMn(-3%甲醛-3mol/L磷酸),本方法测定诺氟沙星、氧氟沙星和环丙沙星的线性范围分别为1.0×10-7～1.0×10-5mol/L,1.0×10-7～1.0×10-5mol/L和3.0×10-7～5.0×10-5mol/L;检出限分别为3×10-8mol/L,3×10-8mol/L,1×10-7mol/L;相对标准偏差(5.0×10-6mol/L氟喹诺酮类药物,n=11)分别为2.6%,1.6%和2.8%。该方法已用于诺氟沙星胶囊中诺氟沙星的含量测定。     

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%.     

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.     

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.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.