固相萃取-高效液相色谱法测定钙强化食品中的维生素D

以含有体积分数为20%的0.95 mol/L柠檬酸水溶液的二甲基亚砜作为维生素D的破壁溶液,利用Chromabond XTR固相萃取柱(14500 mg, 70 mL)对样品进行提取和净化,建立了测定钙强化食品中维生素D的固相萃取-高效液相色谱方法。方法的线性范围为0.1～100.0 μg/mL,线性相关系数为0.999。方法的定性检出限为0.01 μg/g,定量检出限为0.03 μg/g。低(0.1 μg/g)、中(0.5 μg/g)、高(1.0 μg/g)三个浓度水平的加标回收率分别为106.2%,99.5%和100.1%,相对标准偏差小于10%。     

复杂基质中柠檬酸的液相微萃取

建立了一种利用液相微萃取技术进行样品前处理、高效液相色谱进行测定的复杂基质中柠檬酸分析的简便方法。研究表明,该样品前处理方法集萃取、富集、净化为一步,具有快速、有效、绿色的特点;测定方法的线性范围为0.7～600 μg/mL,相关系数为0.9995,检测限为0.27 μg/mL (S/N=3),相对标准偏差小于5%。     

高效液相色谱法同时测定化妆品中的7种磺胺及甲硝唑和氯霉素

建立了化妆品中7种磺胺(磺胺醋酰、磺胺吡啶、磺胺甲基嘧啶、磺胺二甲嘧啶、磺胺甲氧嘧啶、磺胺间甲氧嘧啶、磺胺甲基异唑)和甲硝唑及氯霉素的高效液相色谱测定方法。样品经0.1%甲酸水溶液-乙腈(体积比为8∶2)混合液超声提取后进行液相色谱分析。方法的定量检测限为3～80 μg/g,7种磺胺在20～200 μg/mL时,甲硝唑及氯霉素在40～400 μg/mL时方法的线性关系良好(r≥0.9993)。加标回收率为83.8%～105.3%(7种磺胺的添加水平为50 μg/mL和150 μg/mL,甲硝唑及氯霉素的添加水平为100 μg/mL和300 μg/mL),其相对标准偏差均小于5%。     

反相高效液相色法测定水产品中三聚氰胺

采用反相高效液相色谱法(RP-HPLC) 测定了水产品中的三聚氰胺. 色谱柱为Symmetry C18 (5 μm, 4.6 mm×250 mm), 流动相为含有0.01 mol/L庚烷磺酸钠和0.01 mol/L柠檬酸的乙腈(1+4)水溶液, 检测器为紫外检测器, 检测波长240 nm. 线性范围为1～50 μg/mL, 相关系数为0.9998, 最低检出限为0.24 μg/mL, 样品平均加标回收率为78.8%～96.1%, 相对标准偏差为3.7%～6.4%. 方法可用于水产品中三聚氰胺的测定.     

离子色谱法测定休闲食品中的柠檬酸盐

建立了离子色谱法测定休闲食品中柠檬酸、柠檬酸盐含量的方法。采用标准曲线法定量,柠檬酸浓度在1.0~20.0μg/mL的范围内,线性方程为y=0.049 9x-0.017 4,线性相关系数为0.998 2,方法的检出限为0.015μg/mL,加标回收率为96.9%~101.6%,方法具有简单、快速、重现性好等优点。     

顶空气相色谱法测定盐酸托莫西汀中有机溶剂残留量的研究

建立了盐酸托莫西汀中有机溶剂残留量的顶空气相色谱分析方法.选用大口径HP-快速GC残留溶剂柱为分离柱,FID为检测器,外标法进行定量,并对顶空平衡温度、平衡时间、供试品溶液的制备方法对残留有机溶剂测定的影响进行了研究.甲醇、乙醚、正己烷、乙酸乙酯、四氢呋喃的线性范围分别为 0.41～8.10 μg/mL(r=0.9999)、0.15～3.00 μg/mL(r=0.9995)、0.20～4.01 μg/mL(r=0.9991)、0.32～6.35 μg/mL(r=0.9999)、0.36～7.11 μg/mL(r=0.9999);平均回收率范围96.30%～105.47%,精密度RSD(n=6)2.1%～3.7%;检出限分别为0.2、0.008、0.003、0.04、0.04 μg/mL.     

阻抑动力学荧光法测定柠檬酸

基于在高氯酸介质中柠檬酸能抑制铁(Ⅲ)催化H2O2氧化吡咯红Y的反应，建立了一种测定柠檬酸的动力学荧光分析法。方法的线性范围为0．12-2．4μg/mL，检出限为0．05μg/mL。将方法用于汽水中柠檬酸的测定，回收率为97％-106％。     

HgCl2-头孢噻肟螯合阴离子与碱性三苯甲烷类染料相互作用的共振瑞利散射光谱及其分析应用

在pH为5.3～6.8的Britton-Robinson(BR) 缓冲溶液中, 头孢噻肟钠(CFTM)与HgCl2形成摩尔比为1∶1的螯合阴离子, 它能进一步与结晶紫、甲基紫、乙基紫、亮绿、碘绿、甲基绿和孔雀石绿等碱性三苯甲烷类染料反应形成三元离子缔合物, 导致共振瑞利散射(RRS)的显著增强. 最大RRS峰分别位于367, 367, 340, 367, 340, 340和340 nm附近, 在一定的CFFM质量浓度范围内散射强度与头孢噻肟钠的浓度均呈良好的线性关系. 用结晶紫、甲基紫、乙基紫、亮绿、碘绿、甲基绿和孔雀石绿体系测定头孢噻肟钠的线性范围和检出限(3σ) 分别为0.0090～3.5 μg/mL和2.7 ng/mL, 0.0092～3.5 μg/mL和2.8 ng/mL, 0.013～3.5 μg/mL和4.0 ng/mL, 0.010～3.5 μg/mL和3.1 ng/mL, 0.011～3.5 μg/mL和3.4 ng/mL, 0.012～4.0 μg/mL和3.5 ng/mL以及0.016～3.5 μg/mL和4.7 ng/mL, 其中以结晶紫体系灵敏度最高. 研究了适宜的反应条件和影响因素, 对离子缔合物的组成和离子缔合反应机理进行了探讨, 考察了共存物质的影响, 表明方法有良好的选择性, 据此发展了用HgCl2和碱性三苯甲烷类染料的灵敏、简便、快速测定痕量头孢噻肟钠的新方法.     

反相离子对液相色谱法同时测定11种氟喹诺酮类药物的研究

建立了高效液相色谱-荧光法同时测定11种氟喹诺酮类药物的分析方法.主要研究了流动相、流动相配比及流动相的pH对氟喹诺酮分离的影响.确定了液相色谱分析最佳条件.分离条件为:Xbridge Shield RP C18柱,以V(0.10%三氟乙酸)∶V(乙腈)∶V(甲醇)=89∶4∶7为流动相;检测波长为λex=280 nm和λem＝450 nm.方法检出限为:诺氟沙星、环丙沙星、培氟沙星和恩诺沙星0.007μg/mL,单诺沙星0.002 μg/mL,沙拉沙星和氧氟沙星为0.04 μg/mL,二氟沙星和奥比沙星为0.02 μg/mL,依诺沙星、麻保沙星为0.4 μg/mL,各组分回收率在97%～100.2%,相对标准偏差为0.2%～2.9%.     

毛细管色谱法测定芳香异羟肟酸二丁基锡中有机溶剂残留量

建立了毛细管气相色谱法测定芳香异羟肟酸二丁基锡中的有机溶剂残留量.采用HP-5 (5%苯基甲基聚硅氧烷)毛细管色谱柱,FID检测器.载气为N2,柱温为45 ℃,检测器温度为160 ℃,流速为1.2 mL/min,分流比为20∶1,四氢呋喃为内标进行测定.结果表明: 甲醇、无水乙醇、三氯甲烷、正己烷、苯的线性范围分别为: 7.9～63.2 μg/mL (r=0.9991),8.69～69.52 μg/mL (r=0.9999),19.77～158.16 μg/mL (r=0.9990),295.6～2364.8 μg/mL (r=0.9996),8.74～69.92 μg/mL (r=0.9996),平均回收率分别为104.2%、 98.8%、 97.9%、 103.1%和102.0%,RSD分别为1.6%、 2.3%、 2.1%、 3.8%和1.9% (n=9);检出限分别为3.16、 3.47、 23.90、 1.97和0.87 ng.方法可用于有机溶剂残留量的测定.     

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.     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).