甲磺酸培氟沙星在胶束中的荧光特性研究及应用

在弱酸性介质中,十二烷基硫酸钠(SDS)对甲磺酸培氟沙星有较强的增敏作用,据此建立了胶束增敏荧光光谱法测定痕量甲磺酸培氟沙星的分析方法。本法的线性范围为0.01~1.63mg.L-1,检出限为6.0×10-3μg.mL-1,回收率为99.8%~101.7%,相对标准偏差为0.43%~1.34%。     

牛血红蛋白催化荧光猝灭法测定痕量甲巯咪唑

在NH3·H2O-NH4Cl缓冲溶液中,牛血红蛋白催化H2O2氧化L-酪氨酸产生荧光,甲巯咪唑对该荧光体系具有较强的猝灭作用。据此建立了酶催化荧光猝灭法测定痕量甲巯咪唑的方法。结果表明,甲巯咪唑含量在0.986~14.8μg/L范围内与荧光强度变化值呈线性关系,其线性回归方程为ΔF405 nm=50.923ρ+191.45,相关系数(R²)为0.9945,检出限为为0.32μg/L。方法用于测定药品中甲巯咪唑含量,测定结果的RSD为4.7%,回收率92%~96.3%。     

高效液相色谱荧光法测定全棉织物中微量苯胺和二苯胺

建立了全棉织物中苯胺、二苯胺的高效液相色谱荧光分析方法。全棉织物采用乙腈/甲苯(3/1,V/V)为提取剂,以Carb/PSA固相萃取小柱进行净化,在Kromasil C18柱(250 mm×4.6 mm i.d.,5μm)上以水/乙腈(25/75,V/V)为流动相进行分离,采用荧光法进行检测,荧光检测波长λex为280 nm,λem为340 nm。结果表明,苯胺、二苯胺的低、中、高3个加标水平下的平均回收率分别为97.3%~103.5%和98.0%~103.4%,相对标准偏差分别为1.4%~4.2%和0.98%~4.7%,方法的检出限分别为0.3μg/kg和0.2μg/kg,定量限分别为1.0μg/kg和0.5μg/kg。采用该方法对购自市场的30份全棉织物进行检测,其中1份检出苯胺,2份同时检出苯胺和二苯胺。     

同步荧光光谱法直接测定尿液中卡那霉素

基于卡那霉素对CdTe量子点荧光的增强效应,建立一种直接测定尿液中卡那霉素含量的同步荧光光谱法。研究发现采用同步荧光光谱法,能够有效避免尿液中复杂基质的荧光干扰。在优化实验条件下,卡那霉素浓度在0.2~20.0μg/mL范围内与体系相对同步荧光强度呈良好的线性关系,相关系数为0.9996,检出限为0.005μg/mL。该方法用于尿液样品中卡那霉素含量的直接测定,回收率为96.3%~104.4%。     

高效液相色谱光化学在线衍生技术在11种磺胺药物残留检测中的应用

建立了磺胺药物残留的高效液相色谱-光化学在线衍生-荧光检测方法,并应用于猪肉的检测。样品经过乙腈提取,色谱柱分离后,通过在线光化学衍生后,用荧光检测器进行直接检测。优化后的色谱条件:Eclipse Plus C18柱(250 mm×4.6 mm,5.0μm),流动相为均含0.2%甲酸的乙腈、甲醇和水梯度洗脱,检测激发波长为248 nm,发射波长为350和412 nm。各种磺胺在各自浓度范围内线性相关系数R2>0.999,回收率在85.7%~101.1%之间,RSD为1.9%~6.6%(n=6),各磺胺的检出限(S/N=3)为0.2~3.0μg/kg,定量限(S/N=10)为0.5~10.0μg/kg。     

超高效液相色谱-串联质谱法测定畜禽毛发中4种违禁氟喹诺酮类兽药

采用超高效液相色谱-串联质谱(UPLC-MS/MS)检测技术,通过优化在畜禽毛发中药物的提取、水解、净化等前处理过程,建立了一种测定畜禽毛发中4种违禁氟喹诺酮类药物含量的分析方法。毛发样品经1%十二烷基硫酸钠溶液清洗,乙腈-1%HAc溶液提取,PSA/C18净化管净化,通过C_(18)色谱柱分离,电喷雾串联质谱多反应监测模式测定。结果表明,培氟沙星、氧氟沙星、诺氟沙星、洛美沙星在0.2～20μg/L范围内线性关系良好,相关系数均大于0.993,方法回收率在87.09%～114.95%范围内,相对标准偏差为0.13%～4.92%。培氟沙星、氧氟沙星、诺氟沙星、洛美沙星的检出限分别为0.08、0.05、0.05、0.08μg/kg,定量限分别为0.2、0.1、0.1、0.2μg/kg。该方法样品前处理简单、耗时短、选择性强、灵敏度高,适用于畜禽毛发中上述4种违禁氟喹诺酮类药物的定性定量分析。     

丁基罗丹明B-过硫酸钾催化动力学光度法测定痕量银

报道了以银催化过硫酸钾氧化丁基罗丹明B褪色的动力学光度法测定痕量银的方法。该法的线性范围为0.8~48μg/L,检出限为3.6×10-10g/mL。对浓度为24μg/LAg(Ⅰ)测定的相对标准偏差为2.1%(n=11),表观活化能为87.55kJ/mol。本法应用于磺胺嘧啶银乳膏中银的测定,相对标准偏差为2.3%~2.7%,回收率为97.4%~98.3%。     

联苯胺的三维荧光特性及水污染应急处理

采用荧光分光光度计对溶有联苯胺的水样进行三维荧光扫描,发现位于λex290/λem407处有一个明显的荧光峰。当联苯胺含量在0.2~10μg/L范围内,荧光峰的峰值与联苯胺溶液浓度呈明显的线性相关,相关系数r2=0.9980,回收率在94%~107%,可以通过联苯胺的三维荧光特性快速测定其在水体中的浓度并且判断水体受其污染的程度。采用三维荧光法对联苯胺的浓度进行检测,检测限可达0.1μg/L,符合水质监测要求。粉末活性炭对水中的联苯胺具有良好的吸附去除效果。当联苯胺溶液质量为10μg/L时,采用投加量为15 mg/L的粉末活性炭,去除率可达98.0%,处理后的联苯胺浓度低于《地表水环境质量标准》(GB3838-2002)中的控制值。     

高效液相色谱法测定粮食中玉米赤霉烯酮及其代谢物

采用甲醇-水提取,C18小柱净化,反相HPLC荧光检测器测定了玉米、面粉、小麦样品中的玉米赤霉烯酮及其代谢物和黄曲霉B1。对样品预处理和高效液相色谱测定条件进行了优化,ZON,α-ZOL,β-ZOL和AFTB1的线性范围分别为5.0μg/L~146g/L,25.0μg/L~200g/L,25.0μg/L~160g/L和0.4μg/L~2.0g/L,检出限分别为0.5、2.5、2.5和0.04μg/kg;加标回收率在80.0%~110.0%范围内;日间相对标准偏差为4·5%~9.2%,日内精密度2.7%~7.4%。本方法灵敏准确,易于推广,适用于粮食中玉米赤霉烯酮及其代谢物的检测。     

基于锰掺杂量子点的噁喹酸荧光共振能量转移检测研究

基于噁喹酸对锰掺杂硫化锌量子点的荧光猝灭作用,建立了一种噁喹酸荧光共振能量转移检测方法。噁喹酸对量子点的荧光猝灭是由于生成了新的复合物而造成的静态猝灭,二者相互作用过程中焓变ΔH<0,熵变ΔS<0,分子间作用力为氢键或范德华力。在0~65μg/L线性范围内,噁喹酸质量浓度与量子点荧光抑制率呈现良好的线性关系(R²=0.9911),检出限为0.53μg/L。分别在5μg/L和25μg/L 2个浓度进行加标回收,平均加标回收率为92.2%~96.8%,相对标准偏差为0.6%~2.5%。该方法可应用于水环境中喹啉酮类杀菌剂噁喹酸的快速测定。     

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.     

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.     

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.     

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%).     

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.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.