磷钼蓝体系薄层树脂相吸光光度法测定痕量钼的研究

提出了在酸性条件下,以磷钼蓝反应为基础的薄层树脂相吸光光度法测定钼。此方法灵敏度较高(ε705=8.1×104L·mol-1·cm-1),比液相光度法提高10倍,精密度理想(钼浓度为20μg/25ml,n=6),RSD为2.8%。应用此法测定天然水中钼,线性范围为0～18μg·ml-1,回收率为97%～102%。     

免疫亲和柱高效液相色谱法快速测定牛奶和奶粉中黄曲霉毒素M1、B1、B2、G1、G2

采用单克隆抗体免疫亲和技术作为直接从样品中分离提取黄曲霉毒素的特效手段,提取液挥干后,经衍生用HPLC荧光检测器测定.对鲜奶和高脂奶粉(脂肪含量25%)在0.01,0.05,0.1和0.1,0.5,1.0 μg·L-1水平对黄曲霉毒素M1、B1、B2、G1、G2测定平均回收率(n=10)为66.0%～97.0%;相对标准偏差(n=10)为1.04%～14.0%.方法的检出限低于0.01 μg·L-1(鲜奶), 0.1 g·kg-1(奶粉).     

Zn-5-溴水杨基荧光酮-酒石酸钠-CTMAB 四元显色体系的研究与应用

研究了在碱性介质中 ,Zn-5 -溴水杨基荧光酮 -酒石酸钠 -CTMAB体系光度法测定微量锌的新方法。四元体系的最大吸收峰在 5 6 0 nm处 ,表观摩尔吸光系数为 1.0 8× 10 5 L·mol-1·cm-1。配合物的稳定常数 K′稳 =1.6 7× 10 1 2 ,锌含量在 0～ 10μg/2 5 m L范围内符合比耳定律。此法已用于水样和药物中锌含量的直接测定     

偶氮氯膦Ⅲ吸光光度法测定水中微量钙

探讨了偶氮氯膦Ⅲ吸光光度法测定水中微量钙的最佳测定条件。试验表明,在pH2 80～2.85柠檬酸三钠 盐酸缓冲溶液中,钙离子与偶氮氯膦Ⅲ形成1∶1的配合物,其吸收峰为双峰,最大吸收波长为666nm,水中钙离子含量在0～0.56mg·L-1范围内符合比耳定律,回归方程C=0.0013+2.6382A(mg·L-1),相关系数为0.9999,摩尔吸光系数ε=1.54×104L·mol-1·cm-1,加入EDTA或葡萄糖酸钠等掩蔽剂后,其他金属阳离子在测定条件下对钙离子的测定基本无影响。     

二次微分简易示波伏安法直接测定酒样中半胱氨酸

在 0 .2mol·L- 1NaOH支持电解质溶液中 ,半胱氨酸在二次微分简易示波伏安图阴极支- 0 .4 9V(vs .SCE)处产生一灵敏的峰 ,研究了半胱氨酸在此底液中的示波伏安行为 ,并据上述示波特性建立了二次微分简易示波伏安法直接测定酒中半胱氨酸含量的新方法。校正曲线的线性范围为 3.0× 10 - 6 ～ 5 .0× 10 - 5mol·L- 1,相关系数为 0 .9995 ,检出限为 1× 10 - 6 mol·L- 1,对 1.0×10 - 5mol·L- 1半胱氨酸进行 6次测定的RSD为 1.8%。利用此法测定了啤酒、黄酒及加饭酒中半胱氨酸的含量 ,样品的回收率分别为 94 .2 %、10 1.6 %和 10 2 .2 %。方法具有仪器装置简单、经济 ,方法简便快速、无需通氮除氧以及对样品进行前处理的优点     

微分电位溶出法连续测定饮料中的铜铅镉锌

建立了微分电位溶出法连续测定饮料中痕量铜、铅、镉、锌的新方法。在HAc- Na Ac( p H4 .5)～ 3.5× 1 0 -2 mol·L-1KCl～ 2 .6× 1 0 -5 mol· L-1Hg2 +介质中测定锌 ,然后调节底液为 0 .0 1 mol·L-1HCl,连续测定铜、铅、镉。铜、铅、镉、锌 ,检出限分别为 4 ,0 .1 ,2 ,4 μg· L-1,线性测定范围 Zn2 +:0～ 30 0 μg·L-1,Cu2 +、Pb2 +、Cd2 +:0～ 2 2 0μg· L-1,回收率为 83.4 %～ 1 0 3.3% ,RSD<3.4 % ( n=7)。该法较好解决了金属互化物的影响 ,样品不需消化便可直接测定。     

β-环糊精-二次微分简易示波伏安法测定苯巴比妥

在NaOH底液中 ,β 环糊精能够产生灵敏切口 ,且该切口深度随苯巴比妥 β 环糊精包结物量的增加而变浅。根据 β 环糊精的示波特性 ,建立了用二次微分简易示波伏安法间接测定苯巴比妥注射液中苯巴比妥含量的新方法。苯巴比妥的浓度在 2 .5× 10 - 6 ～ 4 .5× 10 - 5mol·L- 1范围内的回归方程为h(V) =4 .5 5 9- 1.381× 10 4 c(mol·L- 1) ,相关系数为 - 0 .9976 ,检出限为 1.5×10 - 6 mol·L- 1。对于 2 .5× 10 - 5mol·L- 1苯巴比妥 5次测定的相对标准偏差为 2 .7% ,回收率为10 2 .1%。与高效液相色谱和其他方法相比 ,此法具仪器简单、简便快速、无需通氮除氧等特点     

流动注射停流法快速测定环境水样中COD

应用流动注射停流分析技术 ,对环境水样中的COD进行测定。采用KMnO4 作氧化剂和光度分析指示剂 ,葡萄糖作基准物质 ,在反应温度为 95℃ ,停流 5min时 ,COD测定范围为 0～10 0mg·L- 1,检出限为 2mg·L- 1,相对标准偏差为 0 .8% (n =9) ,回收率为 85 %～ 95 %。Cl-<15 0mg·L- 1时不干扰测定     

单一试剂光度法测定血清铜

建立了一种非离子型表面活性剂吐温 80 (Tween 80 )及聚乙二醇辛基苯基醚 (OP)存在下 ,用 2 ( 3 ,5 二溴 2 吡啶偶氮 ) 5 二甲氨基酚 ( 3 ,5 diBr DMPAP)作显色剂直接光度法测定血清铜含量的新方法。用该法测定血清铜 ,显色络合物最大吸收波长为 5 74nm ,线性范围达 63 0μmol·L- 1,表观摩尔吸光系数为 6 91× 1 0 4 L·mol- 1·cm- 1。回收率为 97 2 %～ 1 0 1 5 % ,批内和批间变异系数 (CV)分别为 2 7%与 3 8% ,与原子吸收分光光度法比较相关性良好 ,y =0 98x +0 43 ,r=0 9993 ,P >0 0 5 ,42例健康人血清铜含量为 8 3～ 2 4 9μmol·L- 1( x± 2s)。用该法进行血清铜含量测定 ,准确性和重现性均较好 ,且血清用量少 ,不必去蛋白 ,操作步骤简化 ,具有试剂单一稳定 ,操作简便快速 ,结果灵敏可靠等优点 ,适合临床应用。     

马来酸麦角新碱化学发光传感器的研究

基于发光试剂通过电价键将铁氰化钾固定在阴离子交换树脂上 ,可直接对待测物马来酸麦角新碱进行传感 ,从而建立测定药物马来酸麦角新碱的传感器新方法。其线性范围为 5× 10 -3 ～ 1mg/L ,线性方程为ΔI =10 6 .4 5C +17.10 (R2 =0 .998) ,检出限达到 2 .6 μg/L。对 0 .0 1和 0 .1mg/L的马来酸麦角新碱进行10次测定 ,它们的相对标准偏差 (RSD)分别为 2 .1%、2 .4 %。此传感器的稳定性良好 ,可连续使用 2 0 0次以上。此法已成功地用于马来酸麦角新碱注射液含量的测定以及尿样中马来酸麦角新碱含量的检测     

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.     

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.     

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.     

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.     

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.     

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.     

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.