液相色谱串联质谱法测定鸡蛋中喹诺酮类药物残留

建立了鸡蛋中8种喹诺酮类残留的高效液相色谱串联质谱检测方法。样品用EDTAM cllvaine缓冲液提取,正己烷脱脂后,经HLB固相萃取柱净化,用LC-M S/M S进行检测,内标法定量。8种喹诺酮药物含量在0.5~50μg/kg浓度范围内线性关系良好,相关系数(r)均大于0.999。方法检出限为0.1~0.5μg/kg,定量限为0.3~1.7μg/kg,加标回收率为81.8%~118.4%,相对标准偏差均小于9.6%。该方法适用于鸡蛋中喹诺酮类药物残留量的检测。     

通过式固相萃取净化-液相色谱-串联质谱法测定豆芽中10种喹诺酮类抗生素

建立了超高效液相色谱-串联质谱(UPLC-Ms/Ms)快速检测豆芽中10种喹诺酮类抗生素(QNs)的方法。样品用乙腈-0.1%甲酸水溶液提取后,经PRiME HLB快速净化,氮吹浓缩后,用电喷雾离子源正离子-多反应监测(MRM)模式串联质谱进行检测。在0.25~100μg/L范围内,10种目标物的线性关系良好,其相关系数均大于0.997。方法对两种豆芽基质进行前处理并测定,检出限为1.0μg/kg和2.0μg/kg,定量限为3.0μg/kg和6.0μg/kg。回收率实验结果表明:10种目标物回收率范围为78.1%~106.4%,RSD<8.1%。方法能有效地避免杂质的干扰。     

超高效液相色谱-串联质谱法测定鸡肉中头孢拉定残留

建立测定鸡肉中头孢拉定残留的超高效液相色谱-串联质谱分析方法。鸡肉样品经80%乙腈水溶液提取,PRiME HLB柱固相萃取净化,0.2%甲酸水溶液稀释,采用Waters ACQUITY UPLC HSS T3色谱柱(100 mm×2.1 mm,1.8μm)分离,以0.1%甲酸-0.1%甲酸乙腈为流动相,梯度洗脱,基质加标外标法定量。实验结果表明,头孢拉定在0.5～50.0 ng/mL浓度范围内呈良好的线性关系(R~2=0.9998),定量限为1μg/kg。向空白鸡肉中添加头孢拉定含量为1.00μg/kg、2.00μg/kg、10.0μg/kg时,回收率在77.3%～106.8%之间,相对标准偏差在3.2%～10.5%之间。本方法操作简便、快捷,实验结果准确、稳定,可满足鸡肉中头孢拉定残留量的检测。     

超高效液相色谱-串联质谱测定饲料中镇静剂类和β-受体激素类药物残留

采用超高效液相色谱-串联质谱技术,建立了饲料中8种镇静剂类和15种β-受体激素类药物残留的分析检测方法。样品采用乙腈-1%(体积分数)三氯乙酸水溶液(7∶3,v/v)提取,目标物通过阳离子固相萃取柱净化,经Agilent Zorbax Eclipse Plus C_(18)色谱柱(100 mm×3.0 mm,1.8μm)分离,液相色谱-串联质谱进行检测,标准曲线内标法定量。结果表明:23种目标物在2.0~200.0μg/L内线性关系良好(r20.99)。在饲料样品基质中,目标化合物在5.0、10、50μg/kg 3个加标水平下的平均回收率为75.1%~102.4%,相对标准偏差(RSD)为4.3%~14.3%(n=6)。该方法净化效率高,适用范围广,可用于饲料中镇静剂类和β-受体激素类药物残留筛查和检测。     

通过式固相萃取净化/液相色谱-串联质谱法快速检测水产品中11种青霉素残留

采用通过式固相萃取净化策略去除样品基质中的脂肪和磷脂等杂质干扰,结合液相色谱-串联质谱检测,建立了水产品中11种青霉素残留的同时快速分析方法。样品经80%乙腈水溶液提取,Oasis PRi ME HLB通过式固相萃取柱净化,C_(18)色谱柱分离,0.05%甲酸乙腈溶液和0.05%甲酸水溶液梯度洗脱,多反应监测正离子模式扫描,内标法定量。11种目标物在相应浓度范围内线性关系良好,相关系数不低于0.99,检出限为0.30~1.5μg/kg。基质加标回收率为85.5%~110%,相对标准偏差(RSD)为5.9%~14.3%。该方法前处理操作简便,灵敏度和准确度高,可实现水产品中多种青霉素药物残留的同时快速测定。     

液相色谱串联质谱同位素稀释法对蜂王浆中10种硝基咪唑类药物残留的检测

建立了液相色谱-电喷雾串联质谱法(LC-ESIMS/MS)测定蜂王浆中10种硝基咪唑类药物残留的分析方法。蜂王浆样品经甲醇沉淀蛋白质,弱碱性条件下乙酸乙酯提取硝基咪唑类药物残留,Oasis(HLB)和C18固相萃取柱净化后,通过液相色谱-质谱联用技术进行检测(正离子方式,多反应监测模式),采用同位素稀释内标法或外标法进行定量。方法的线性范围为5.0~60μg/kg,相关系数大于0.999,在10、20、50μg/kg加标水平的回收率为70%~105%,相对标准偏差小于12.7%,定量下限均为10μg/kg。该方法定量准确,适用于对蜂王浆中硝基咪唑类药物残留的确证检测。     

超高效液相-串联质谱法同时测定蜂蜜中15种喹诺酮类药物残留

建立了蜂蜜样品中15种喹诺酮类兽药残留的超高效液相色谱-串联质谱检测方法。蜂蜜样品用磷酸盐缓冲溶液溶解提取后,用Oasis HLB固相萃取柱净化,超高效液相-电喷雾串联四级杆质谱检测,外标法定量。测定时用Acquity UPLC BEHC18色谱柱(50 mm×2.1 mm,1.7μm)分离,体积分数0.1%甲酸溶液-乙腈系统梯度洗脱,质谱测定采用多重反应监测(MRM)模式。15种喹诺酮类兽药的检出限均低于或等于1.0 ng/mL,回收率均在78.6%～112.9%范围内,相对标准偏差均在10%范围内。该方法各项指标均能满足国内外各项法规的要求,可用于蜂蜜样品中喹诺酮类药物残留的定量和定性检测。     

通过型固相萃取-液相色谱-高分辨质谱法快速测定粮谷中17种酰胺类农药残留量

应用PRiME HLB固相萃取柱通过式净化技术,采用液相色谱-四极杆静电场轨道阱高分辨质谱(LC-Q Orbitrap),建立了粮谷中17种酰胺类农药的检测方法。样品经乙腈提取,PRiME HLB固相萃取柱净化,在GL Intersil ODS-3色谱柱上以0.5%甲酸水和乙腈为流动相进行梯度洗脱,四极杆静电场轨道阱高分辨质谱以Full Scan/ddMS^2模式进行检测。结果表明,各组分在各自浓度范围内线性关系良好,相关系数均大于0.996。方法定量限在0.5~5μg/kg之间。待测物在5.0,10.0,50.0μg/kg 3个浓度水平下加标回收率在70.4%~101.6%之间,相对标准偏差在2.7%~10.8%之间。该方法可用于粮谷中酰胺类农药的测定。     

超高效液相色谱-电喷雾串联质谱法同时分析鸡肉中7种氟喹诺酮类药物残留

建立了一种同时测定鸡肉中7种氟喹诺酮类药物残留的超高效液相色谱-电喷雾串联质谱确证分析方法(UPLC-ESI-MS/MS)。样品经酸化乙腈提取、正己烷脱脂和HLB固相萃取柱净化,采用ACQUITY UPLCTM BEH C18色谱柱(50 mm×2.1 mm,1.7 μm)分离,以0.1%甲酸水溶液和乙腈作为流动相进行梯度洗脱,电喷雾质谱检测,正离子多反应监测模式进行定性和定量分析。7种药物在5～100 μg/kg范围内线性关系良好,相关系数(r2)均大于0.99;以5,25,50 μg/kg3个浓度水平进行添加回收试验,7种药物的平均回收率在79.2%～108.6%之间,相对标准偏差为4.2%～8.9%,方法的检出限(LOD)为0.2～1.4 μg/kg。方法重现性好、灵敏度高、分析时间短、确证能力强,适用于鸡肉中氟喹诺酮类药物多残留的确证检测。     

通过式固相萃取净化/高效液相色谱-串联质谱法快速测定水产品中6种麻醉剂残留

建立了一种快速测定水产品中6种麻醉剂(普鲁卡因、利多卡因、布比卡因、丁卡因、3-氨基苯甲酸乙酯甲基磺酸盐、苯佐卡因)的高效液相色谱-串联质谱分析方法。样品以水和1%甲酸乙腈提取,提取液经PRiME HLB固相萃取柱净化,以乙腈和0.1%甲酸水溶液为流动相梯度洗脱,ZORBAX Eclipse XDB-C_(18)色谱柱(3.0 mm×150 mm,3.5μm)分离,多反应监测(MRM)正离子模式检测,外标法定量。结果表明,6种组分在各自质量浓度范围内线性关系良好,相关系数(r~2)为0.993 8～0.998 7,方法检出限(LOD)为1.5～6.0μg/kg,定量下限(LOQ)为5.0～20μg/kg,平均加标回收率为76.8%～110%,相对标准偏差为4.2%～11%。该方法前处理操作简单、快速、准确、灵敏,适用于水产品中6种麻醉剂残留的快速测定。     

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.