反相高效液相色谱法同时测定4种氟喹诺酮类药物在鸡可食性组织中的残留

建立了一种可同时测定鸡可食性组织中环丙沙星、达氟沙星、恩诺沙星及沙拉沙星等多种残留的反相高效液相色谱 -荧光分析法。鸡的肌肉、皮和脂、肝、肾等4种组织经不同pH值的磷酸二氢钾缓冲溶液匀浆提取,上清液通过C18固相萃 取柱净化,以流动相洗脱。洗脱液经液相色谱分离后,用荧光检测器进行检测(激发波长280 nm, 发射波长450 nm),外标 法定量。对鸡的4种组织进行添加回收率测定,结果显示方法在添加水平为20~300 μg/kg时药物的回收率约为53.9%～93.4%,批间回收率测定值的相对标准偏差低于23%;环丙沙星、恩诺沙星、沙拉沙星 的定量检出限为20 μg/kg,达氟沙星为4μg/kg。方法简单、快速,能满足常规兽药残留检测的需要。     

高效液相色谱法同时检测8种喹诺酮类兽药残留量

建立了吡哌酸、氧氟沙星、环丙沙星、单诺沙星、恩诺沙星、沙拉沙星、(噁)喹酸和氟甲喹8种喹诺酮类兽药残留量的高效液相色谱-荧光检测方法. 方法的线性范围: 30～2000 μg/kg, 定量限为30 μg/kg, 检出限为5 μg/kg (吡哌酸为20 μg/kg). 该方法采用基质分散和微波萃取技术进行样品的前处理, 回收率为70.0%～99.5%, 相对标准偏差1.0%～8.5%. 并同固相萃取方法进行了比较, 分别使用了RPS、HLB、MAX 3种固相萃取柱, 其回收率均低于本法. 确立了以Aglient XDB-C18 (5 μm, 150 mm×4.6mm i.d.)色谱柱, H3PO4-纯水-三乙胺-乙腈(pH 3.0)为流动相的最佳色谱条件, 吡哌酸、氧氟沙星、环丙沙星、单诺沙星、恩诺沙星、沙拉沙星的检测波长为: 激发波长285 nm, 发射波长460 nm;(噁)喹酸和氟甲喹为: 激发波长325 nm, 发射波长365 nm. 方法可满足兽药残留检测要求.     

高效液相色谱法测定鸡蛋中呋喃唑酮的残留量

采用基体固相扩散和固相萃取相结合的技术,对鸡蛋中呋喃唑酮残留进行了提取和净化处理,建立了高效液相色谱法检测鸡蛋中呋喃唑酮残留量的方法。对呋喃唑酮在C18固定相和硅胶固相萃取柱上的保留行为进行了研究。采用液相色谱分离,外标法定量,呋喃唑酮标准溶液的峰面积与样品浓度在5μg／L～2．5mg／L范围内呈良好的线性关系,线性回归系数大于0．9999。鸡蛋样品中呋喃唑酮不同加入量的平均回收率在80．2％～91．1％;相对标准偏差在2．0％～9．5％;最低检出限为10μg／kg。分析方法具有良好的重现性．批内、批间定量结果的相对标准偏差均小于10％。     

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。     

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%.     

高效液相色谱法快速测定鸡蛋中5种氟喹诺酮类药物残留

建立了一种检测鸡蛋中环丙沙星、达氟沙星、恩诺沙星、二氟沙星及沙拉沙星残留的高效液相色谱方法。该方法前处理简便快速,样品经低浓度乙腈结合加热促使蛋白质快速沉淀,正己烷脱脂,分离清液后进高效液相色谱仪分析。流动相为0.05 mol/L磷酸/三乙胺溶液-乙腈溶液(80∶20),荧光检测器的激发波长为280 nm,发射波长为450 nm。该方法对环丙沙星和二氟沙星的定量下限为5μg/kg,达氟沙星的定量下限为0.5μg/kg,恩诺沙星的定量下限为2.5μg/kg,沙拉沙星的定量下限为10μg/kg。在定量下限及低、中、高4种加标浓度下,5种氟喹诺酮类药物的平均回收率为92.2%~107.1%,批内相对标准偏差(RSD)为0.6%~5.8%,批间相对标准偏差为1.5%~5.0%。方法具有前处理简单、环保、快捷、准确度和灵敏度高等优点,适合生产线和流通环节鸡蛋样品的快速检测。     

蜂蜜中14种喹诺酮类药物残留的高效液相色谱-串联质谱测定

建立了同时测定蜂蜜中14种喹诺酮类药物残留的高效液相色谱-串联质谱分析方法.蜂蜜中喹诺酮类药物残留用0.05 mol/L磷酸盐缓冲溶液(pH＝3.0)提取,样液过滤后,经Oasis HLB固相萃取柱净化,氢氧化铵-甲醇溶液(体积比1:19)洗脱,蒸干定容后,用反相液相色谱分离,电喷雾正离子模式离子化,用多反应监测方式(MRM)监测,三重四极杆质谱测定.环丙沙星在0.4～100.0μg/kg,噁喹酸在0.4 ～50.0μg/kg,恩诺沙星、沙拉沙星、双氟沙星、依诺沙星、诺氟沙星在1.0～100.0μg/kg,氧氟沙星、单诺沙星、氟罗沙星、奥比沙星、麻保沙星在1.0～50.0μg/kg,司帕沙星、氟甲喹在2.0 ～100.0μg/kg范围内呈线性关系,相关系数r>0.997,在2.0、5.0、10.0、50.0 μg/kg 4个添加水平,回收率为66% ～111%,相对标准偏差(RSD)为1.3% ～13.6%.该方法操作简便,稳定性好,选择性好,灵敏度高,其检出限达1.0μg/kg.     

高效液相色谱法检测六种氟喹诺酮类兽药残留前处理的优化

建立了一个检测动物源性食品中6种氟喹诺酮类药物残留的高效液相色谱方法。不同基质的样品前处理对检测影响较大:鱼、肉及肝脏等样品需经过乙腈-0.1 mol/L KH2PO4缓冲液提取,乙腈饱和的正己烷洗涤去除油脂;蛋及乳制品样品用正己烷饱和的乙腈提取,乙腈饱和的正己烷去脂。目标化合物采用高效液相色谱-荧光检测器检测,外标法定量。对市售鸡肉、猪肉、鸡蛋进行检测,添加10、20、50、100μg/kg浓度水平时,回收率在82%~105%之间,相对标准偏差在4%~12%之间,方法的检出限诺氟沙星、环丙沙星、沙拉沙星及单诺沙星为5.0μg/Kg,恩诺沙星、达氟沙星为3.0μg/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。     

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0.5 μg/kg,沙拉沙星为1.0 μg/kg,氟甲喹为0.1 μg/kg.     

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.     

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.     

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.     

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.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.