固相萃取-高效液相色谱法测定鸡肝中磺胺类药物残留量

建立了一种鸡肝中7种磺胺类药物残留量固相萃取-反相高效液相色谱分析方法。对样品提取后磺胺类药物在氨基键合固相萃取柱上的保留行为进行了研究。采用Intersil ODS-3 C18柱,以甲醇-乙腈冰．乙酸为流动相梯度洗脱,进行高效液相色谱分离,二极管阵列检测器检测,外标法定量。7种磺胺类药物标准曲线的线性回归系数均在0．999以上,线性范围为25—10000μg／L;检出限在8—12μ／kg之间;在50、100、200μg／kg^3个添加浓度水平下添加回收率在69．6％-91．3％范围内;相对标准偏差在4．3％-8．0％之间。该方法具有快速、灵敏、环保的特点,符合现行兽药残留分析的要求。     

高效液相色谱-二极管阵列检测法同时分析兽药粉剂中11种磺胺类药物

建立了高效液相色谱-二极管阵列检测法同时测定兽药粉剂中11种磺胺类药物的分析方法。试样采用95%乙腈提取,经碱性氧化铝固相萃取小柱净化,15%乙腈复溶残渣后用Agilent TC-C18色谱柱分离,0.017 mol/L磷酸溶液和乙腈为流动相进行梯度洗脱,二极管阵列检测器进行检测。结果表明,在优化实验条件下,11种磺胺类药物的色谱分离和相应光谱图匹配理想;在0.25～10.0 mg/L范围内线性关系良好;兽药粉剂中添加0.5～5.0 mg/kg水平的11种磺胺类药物的回收率在67%～97%之间,相对标准偏差为1.5%～9.9%;以3倍信噪比(S/N=3)结合相应光谱图计算得11种磺胺类药物的检出限均为0.25 mg/kg。     

固相萃取-梯度洗脱高效液相色谱法同时检测饲料中十三种磺胺类药物

建立了一种同时检测饲料中十三种磺胺类药物含量的方法,样品用磷酸盐缓冲液提取,HLB固相萃取小柱净化,梯度洗脱-HPLC分析,方法定量下限为0．5mg／kg,在0．5～10．0mg／kg添加水平上的回收率为63．6％～118．2％,相对标准偏差4．78％～17．24％,方法简便．适用于饲料中低含量磺胺类药物检测．     

水产品中14种磺胺类药物残留的HPLC法同时测定

建立了HPLC法同时分离并检测鱼、虾等水产品中14种磺胺类抗菌药物。样品经无水硫酸钠脱水后,乙腈提取药物,再用乙腈饱和正己烷脱脂净化。以乙腈-3％冰醋酸为流动相,采用梯度淋洗,于268nm波长处检测．该法的检出限为0．01～0．02mg／kg,样品的加标回收率为66％～92％。     

反相高效液相色谱／质谱法同时测定鸡肉中5种喹诺酮药物残留

采用反相高效液相色谱／四级杆串联质谱（RP-HPLC／MS／MS）同时测定鸡肉中的5种喹诺酮药物（quinolones，QNs）。均质后的鸡肉样品采用磷酸盐缓冲溶液和乙腈的混和溶液提取。提取液经正己烷液-液分配（LLP）去除脂肪后，用C18固相萃取（SPE）柱净化，氨化甲醇洗脱，洗脱液用氮气吹干，流动相定容后，分析物采用LC／MS／MS电喷雾电离（ESI），正离子，多反应监测（MRM）模式检测，外标法定量。在添加浓度2．5～10μg/kg范围内，5种QNs的回收率在79．8％～95．1％之间；相对标准偏差（RSD）均小于11．7％。环丙沙星、丹诺沙星、恩诺沙星检出限（LOD）为0．5μg／kg，沙托沙星为1．0μg／kg，氟甲喹为0．1μg／kg。     

HPLC法对鱼肉中3种四环素类和5种氟喹诺酮类兽药残留的同时测定

建立了水产品中四环素类和氟喹诺酮类兽药多残留同时检测的高效液相色谱分析方法。样品经甲醇-水（体积比2：8,pH5．3）提取,C18固相萃取小柱净化,以甲醇-丙二酸＋氯化镁水溶液作流动相,梯度洗脱,紫外检测器检测。对样品前处理和色谱分析条件进行了优化,8种抗生素（土霉素、四环素、金霉素、沙拉沙星、恩诺沙星、达氟沙星、环丙沙星、单诺沙星）在0．1～10mg／L范围内线性关系良好。方法的检出限（S／N=3）为0．011～0．051mg／kg,定量下限（S／N=10）为0．035～0．17mg／kg,平均加标回收率为81％～96％,相对标准偏差（RSD）为2．5％～10．5％。该方法适用于水产品中抗生素多残留的测定。     

高效液相色谱-电化学阵列检测器检测10种磺胺药物在鸡肉中的残留

建立了一步有机溶剂提取、HPLC分离、多孔石墨电极阵列检测器检测10种磺胺类药物在鸡肉中残留量的方法。采用乙腈-氯仿混合液(乙腈：氯仿=10：1)提取，10种磺胺药物的提取收率均大于50％；研究了磺胺类药物在多孔石墨电极上的氧化还原特征，确定检测电势为455，560，630，670和710mV；优化了HPLC分离条件，Hypersil BDS C-18色谱柱，pH5、30mmoL／L磷酸二氢钠、8．5％-37．5％乙腈(V/V)线性梯度洗脱，40min内实现10种磺胺药物的基线分离，鸡肉中提取的杂质不干扰样品分离；方法的检出限(S/N=3)为磺胺二甲异喔唑(SIA)40μg／kg及磺胺(SA)、磺胺嘧啶(SDZ)、磺胺甲基嘧啶(SMR)、磺胺二甲基嘧啶(SMZ)、磺胺吡啶(SPD)、磺胺噻唑(STZ)、磺胺甲噻二唑(SMTZ)、磺胺氯哒嗪(SCP)和磺胺甲基异喔唑(SMX)等分别为20μg／kg，在0．1—2．0mg/L浓度范围内各磺胺类药物与其响应信号呈现良好的线性关系，相关系数(r)均大于0．9978；电极再生方法简单，可实现在线清洗，适用于食用畜禽产品中磺胺类药物残留量的分析。     

高效液相色谱法测定动物组织中8种磺胺类药物残留量

提出了一种快速、准确地同时测定动物组织中磺胺类药物残留量的检测方法。样品中加入无水硫酸钠后，用乙腈均质、提取，在离心后的沉淀物中加入乙腈，再次提取，合并乙腈提取液。提取液用乙腈饱和正己烷溶液净化，去除脂肪和杂质，用高效液相色谱方法进行测定。通过优化色谱条件，利用紫外检测器(VWD)或二极管阵列检测器(DAD)对8种磺胺类药物残留进行同时测定，测定结果的相对标准偏差为5.1％～12.8％，平均回收率为62.7％～105．1％，检出限为10μg/kg。     

超高效液相色谱法测定畜禽肉中10种磺胺类药物残留量

提出了超高效液相色谱法测定畜禽肉中10种磺胺类药物残留量的方法。样品经乙酸-乙腈(1+99)混合溶剂提取,旋转蒸发后用乙酸(0.1+99.9)溶液溶解,正己烷净化。以AcquityUPLC BEH C18色谱柱为分离柱,以不同体积比混合的乙腈和乙酸(0.1+99.9)溶液为流动相进行梯度洗脱,用二极管阵列检测器于波长265nm检测。10种磺胺类药物的质量浓度与其峰面积均在0.05～10mg.L-1范围内呈线性关系,检出限(3S/N)为2～6μg.kg-1。方法的回收率在70.8%～93.3%之间,相对标准偏差(n=9)在2.7%～7.7%之间。     

柱后衍生-荧光检测高效液相色谱法快速测定鲜牛奶中链霉素残留量

牛奶样品经磷酸溶液提取，提取液用苯磺酸阳离子交换柱和C18固相萃取柱净化，链霉素残留液用甲醇从C18固相萃取柱上洗脱，经旋转蒸发器减压蒸干，残渣用0．01mol／L庚烷磺酸钠溶液溶解，用柱后衍生-高效液相色谱荧光检测器在激发波长263nm和发射波长435nm测定．方法线性范围为0.01～0．10mg／kg；在0．01～0．10mg／kg范围，三个添加水平的回收率为78．3％～80．2％，变异系数(CV)为7．4％～12．4％，方法检出限为0．005mg／kg．     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

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.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.