四种阴离子的毛细管电泳电导检测(英文)

 采用柠檬酸 柠檬酸钠作为缓冲体系 ,使用负高压 ,对Cl-,NO3 -,HCO3 -和H2 PO4 -等 4种常见阴离子进行了分离检测 ,研究了缓冲剂的种类、浓度、pH值及操作电压对分离的影响。在选定的条件下 ,4种离子的定量线性范围 :Cl-5 0× 10 -5mol/L～ 2 5× 10 -3 mol/L ,NO3 -6 0× 10 -5mol/L～ 2 0× 10 -3 mol/L ,HCO3 -5 0× 10 -6mol/L～ 2 0× 10 -4 mol/L ,H2 PO4 -6 0× 10 -5mol/L～ 1 0× 10 -3 mol/L ;检出限 :Cl-1 5× 10 -5mol/L ,NO3 -3 0×10 -5mol/L ,HCO3 -1 0× 10 -6mol/L ,H2 PO4 -2 0× 10 -5mol/L ;峰面积的RSD (n =6 ) :Cl-3 1% ,     

β-环糊精存在下阳离子表面活性剂的毛细管电泳电导法测定

基于H3 BO3 与 β CD配合成大阴离子 ,与不同的阳离子表面活性剂作用不同 ,建立了快速分离检测阳离子表面活性剂的毛细管电泳电导法。研究了H3 BO3 与 β CD的浓度 ,缓冲液的酸度和浓度对分离的影响。在优化的实验条件下 ,溴化四丁基铵 (TBAB)、溴化十二烷基三甲基铵 (DTAB)、溴化十六烷基三甲基铵(CTMAB)阳离子表面活性剂 10min内完全分离 ,峰形良好。线性范围分别为TBAB 10 -3 ～ 10 -5mol/L ,DTAB1.0× 10 -3 ～ 5 .0× 10 -6mol/L ,CTMAB 1.0× 10 -3 ～ 5 .0× 10 -6mol/L。检测限分别为TBAB 7.5× 10 -6mol/L ,DTAB 1.7× 10 -6mol/L ,CTMAB 1.0× 10 -6mol/L。方法用于合成水样分析 ,结果令人满意     

流动注射化学发光法测定稀土矿中三价铽

NaIO4H2O2是弱的化学发光体系,而Tb3+与EDTA形成的络合物对NaIO4H2O2的化学发光有显著的增敏作用,而且Tb3+EDTANaIO4H2O2体系的相对发光强度与Tb3+浓度成正比,在选定的最佳实验条件下,Tb3+的浓度与化学发光强度在1.0×10-7～1.0×10-5mol/L之间呈良好的线性关系;检出限为8.0×10-9mol/L;对浓度为1.0×10-6mol/L的Tb3+进行12次平行测定,相对标准偏差为3.2%。利用该方法成功的测定了矿样和稀土氧化物中的铽的含量。     

Zr(Ⅳ)-桑色素络合物在碳糊电极上的二次导数吸附伏安法测定Zr的研究

研究了Zr(Ⅱ)-桑色素络合物在碳糊电极正电位区的吸附伏安行为,并利用其在0.74V处的二次导数吸附氧化峰电流与Zr(Ⅳ)浓度为6.0×10-9～2.0×10-6 mol/L呈线性而测定Zr;检出限为3.0×10-9 mol/L(S/N=3).最佳测定条件为2.0 mol/L HCl、1.0×10-5 mol/L桑色素;富集电位为0V(vs.SCE);扫描速度为250 mV/s.该法不需萃取分离,可直接用于岩石样品中Zr的测定,结果满意.     

二次微分简易示波伏安法用于胃舒平片剂中铝的测定

向3.75×10 -5mol/LCd2 + -4.0×10 -5mol/L芦丁 -0.05mol/LKNO3-0.05mol/LNa2B4O7 中加入Al3 +时 ,二次微分简易示波伏安图上由Cd -芦丁配合物产生的峰高在一定范围内随Al3 + 浓度的增加线性降低 ,据此建立了测定Al3 +的二次微分简易示波伏安法 ;线性范围为1.0×10 -6～6.5×10 -4mol/L ,检出限为6.0×10-7 mol/L ;该法用于胃舒平片剂中铝的测定的相对标准偏差为3.3 %(n=5)。     

血红蛋白模拟过氧化物酶催化反应体系的极谱分析

用极谱分析法研究了血红蛋白催化H2O2氧化邻苯二胺(OPD)的反应体系.血红蛋白具有类似过氧化物酶的功能,它能够催化OPD-H2O2的反应生成一种具有电化学活性的产物,该产物在滴汞电极上-0.64V(vs.SCE)产生一个峰形良好的极谱还原峰.优化了血红蛋白的催化反应条件和催化反应产物的极谱测定条件 在最佳条件下,该体系可用于血红蛋白含量的测定,线性范围为2.0×10-9～2.0×10-7mol/L,检测限为1.0×10-9mol/L;也可用于痕量H2O2的测定,线性范围为1.0×10-6～2.0×10-4mol/L,检测限为1.0×10-6mol/L.     

溶出伏安法同时测定水中痕量铀和镍

本文报道了同时测定钴和镍的一种方法.在 0.01mol/L NH_3·H_2O-0.01mol/LNH_4Cl-3.0×10~(-5)mol/L安息香缩氨基硫脲(BTSC)溶液中,钴(Ⅱ)和镍(Ⅱ)均产生非常灵敏的还原波,其峰电位分别是:-0.94和-0.75V(vs.SCE),峰电流与钴和镍的浓度分别在2.0×10~(-8)~1.0×10~(-6)和1.0×10~(-8)~8.0×10~(-7)mol/L范围内成直线关系,该方法用于测定水中痕量钴和镍,相对标准偏差分别为1.4~2.0%和2.1~2.5%,回收率分别在98.0%~101.8%和97.9%~102.1%之间.     

磷钼杂多酸光度法测定吲哚乙酸

研究了吲哚乙酸与磷钼杂多酸在浓度为 0 .0 3 mol/L的硫酸介质中发生氧化还原反应 ,形成的还原产物 (钼蓝 )在 NH3-NH4Cl缓冲溶液 (p H8.4)中最大吸收波长为 314 nm,表观摩尔吸光系数 ε值为 3.5 4× 10 4L· mol-1·cm-1 ,吲哚乙酸含量在 5 .0× 10 -7～ 5 .0× 10 -5 mol/L范围内符合比尔定律 ,检出限为 1.0× 10 -7mol/L,对 2 .0 0× 10 -5 mol/L吲哚乙酸测定 10次的相对标准偏差为 6 .42 % ,加标回收率为 94.2 %～ 10 0 .1%     

青霉素 V钾的二次微分简易示波伏安法测定

利用青霉素 V钾在 pH=7的 KH2PO4-Na2HPO4缓冲溶液中产生切口的示波特性 , 提出了一种药片中青霉素 V钾的测定方法 - - 二次微分简易示波伏安法 ; 校正曲线的线性范围为 2.0× 10-5～ 2.0× 10-4 mol/L, 检出限为 8× 10-6 mol/L; 对 7.0× 10-5 mol/L青霉素 V钾 8次测定结果的相对标准偏差为 1.6% ; 实验结果表明该法具有分析速度快、仪器装置简单以及药片中的淀粉等物质不干扰测定的优点 .     

5-羟色胺在碳纤维微电极上的电化学测定及伏安行为研究

本文研究了5 羟色胺在Na2HPO4 KH2PO4(pH6.0)缓冲溶液中,于自制的碳纤维微电极上的伏安行为。在此缓冲溶液中5 羟色胺有一对氧化还原峰,峰电位分别为0.2V和0.4V。峰电流与5 羟色胺的浓度分别在4.0×10-6～4.0×10-5mol/L和5.0×10-6～5.0×10-5mol/L范围内呈良好的线性关系,检出限分别为4.70×10-6mol/L和1.76×10-6mol/L。同时利用多种电化学方法求出了动力学参数。     

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.     

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.     

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.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

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.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

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.