固相萃取-高效液相色谱法检测牛奶和猪肉中5种β-内酰胺类抗生素

建立了牛奶和猪肉样品中氨苄西林、青霉素V、青霉素G、苯唑西林和氯唑西林等5种β-内酰胺类抗生素残留量的高效液相色谱(HPLC)测定方法。实验采用固相萃取法(SPE)富集抗生素残留,考察了样品前处理方法;并对色谱分离条件加以优化,在C18色谱柱上以乙腈-0.1%氨水进行梯度洗脱,可在10min内实现5种抗生素的分离与检测,检测波长为210nm。方法可用于动物性食品中上述抗生素残留的同时检测。     

超高效液相色谱-串联质谱法对动物源性食品中13种β-内酰胺类药物残留的检测

建立了动物源性食品中青霉素G、青霉素V、阿莫西林、羧苄西林、氨苄西林、苯唑西林、氯唑西林、萘夫西林、头孢喹肟、头孢氨苄、头孢拉定、头孢唑啉和头孢哌酮13种β-内酰胺类药物残留检测的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法.样品经水和乙腈提取后,用正己烷去除脂肪,再用C18固相萃取柱净化,浓缩后用BEH C18色谱柱(50 mm×2.1 mm,1.7 μm)分离 ,以0.1%甲酸乙腈溶液和0.1%甲酸水溶液为流动相进行梯度洗脱,电喷雾正离子(ESI+)模式电离,多反应监测(MRM)模式检测.结果表明:在5 ～500 μg/L的基质匹配标准溶液内13种β-内酰胺类药物均有良好的线性关系,相关系数(r)均大于0.998;样品中13种β-内酰胺类药物的检出限(LOD)均为1 ng/g,定量下限(LOQ)均为2 ng/g;在5 ～50 ng/g的加标范围内13种β-内酰胺类药物的平均回收率为79% ～99%,相对标准偏差(RSD)小于13.5%.     

超高效液相色谱-四极杆-飞行时间质谱快速筛查蔬菜中18种农药残留

建立蔬菜中18种农药残留的超高效液相色谱-四极杆-飞行时间质谱(UPLC-Q-TOF MS)快速筛查方法.样品经1％乙酸乙腈提取,QuEChERS法净化,经C18色谱柱(100 mm×3.0 mm,1.8 μm)分离,以乙腈与含0.1％甲酸的2 mmoL/L甲酸铵溶液为流动相,梯度洗脱,UPLC-Q-TOF MS检测,...     

肉豆蔻中赭曲霉毒素的测定及赭曲霉毒素产毒菌的分离鉴定

建立了同时测定肉豆蔻中3种赭曲霉毒素的超高效液相色谱-串联质谱法(UPLC-MS/MS).样品经70％甲醇超声提取,HLB柱净化,采用Agilent Proshell 120 EC C18色谱柱,以乙腈(含0.1％甲酸)-水(含0.1％甲酸)为流动相进行梯度洗脱,于电喷雾离子源正负离子模式下多反应监测模式检测.结果表明...     

基于超高效液相色谱-四极杆-飞行时间串联质谱联用技术的黄英咳喘糖浆化学成分分析

采用超高效液相色谱-四极杆-飞行时间串联质谱联用技术(UPLC-Q-TOF-MSE),结合UNIFI科学信息系统分析鉴定黄英咳喘糖浆中化学成分.使用Waters CORTECS Shield RP18 C18色谱柱(4.6 mm×100 mm,2.7 μm)和乙腈(A)-0.1％甲酸水溶液(B)流动相系统进行梯度洗脱;...     

QuEChERS前处理-液相色谱-串联质谱测定果蔬中18种弱酸性农药残留

建立了液相色谱-串联质谱同时快速测定水果蔬菜中唑菌酮等18种弱酸性农药残留的方法。样品采用1%乙酸-乙腈提取、无水硫酸镁及乙酸钠盐析、C18分散固相萃取净化。考察了唑菌酮在电喷雾离子源的离子化效率,发现在负离子电离模式下加乙酸铵能显著提高唑菌酮的离子化效率。液相色谱以CSH C18色谱柱进行分离,5 mmol/L乙酸铵-乙腈为流动相进行梯度洗脱。质谱分析采用电喷雾负离子电离、多反应监测模式,以基质匹配校准曲线外标法进行定量分析。18种农药在8种基质(青花菜、大葱、胡萝卜、荷兰豆、香菇、苹果、猕猴桃、橙)中3个添加水平(10,20,100μg/kg)的回收率为71.4%~119.7%,相对标准偏差为1.2%~10.0%。18种农药的定量下限(S/N≥10)为0.1~2.0μg/kg。方法简便、灵敏、环保,适用于水果蔬菜中唑菌酮等18种弱酸性农药残留的测定。     

高效液相色谱电喷雾质谱快速鉴定粉葛中C-苷及O-苷同分异构体

采用高效液相色谱(二极管阵列)/电喷雾质谱联用系统( HPLC-PDA-ESI-MSn)快速鉴定中药粉葛中C-苷及O-苷异黄酮同分异构体.选用Hypersil Gold C18(150 mm×2.1 mm×3 μm)色谱柱,以水(含0.1％甲酸)-乙腈为流动相进行梯度洗脱,研究了粉葛中11种异黄酮类化合物的正离子一级、...     

液相色谱串联质谱法测定果蔬中的唑虫酰胺、氟啶虫酰胺、氯虫苯甲酰胺及氟虫双酰胺残留

建立了同时测定蔬菜和水果中唑虫酰胺、氟啶虫酰胺、氯虫苯甲酰胺和氟虫双酰胺残留量的液相色谱-串联质谱(LC-MS/MS)分析方法。样品经乙腈提取,过滤后进行盐析,上层有机相经QuEChERS方法净化浓缩后,用乙腈-水(体积比20∶80)定容进行分析。采用XBridgeTMC18色谱柱,以0.1%甲酸溶液-乙腈体系进行梯度洗脱,MRM方式测定,基质外标法定量。在优化条件下,唑虫酰胺和氟啶虫酰胺的线性范围为0.075~2.0 mg.L-1,氯虫苯甲酰胺和氟虫双酰胺为0.015~0.40 mg.L-1,线性相关系数均不低于0.998。唑虫酰胺、氟啶虫酰胺、氯虫苯甲酰胺及氟虫双酰胺在蔬菜和水果样品中的检出限(S/N=3)为0.000 8、0.005、0.002、0.000 5 mg.kg-1。蔬菜和水果中4种农药在0.05~5.0 mg.kg-1(氟啶虫酰胺和唑虫酰胺)和0.01~1.0 mg.kg-1(氟虫双酰胺和氯虫苯甲酰胺)加标范围内的回收率为80%~95%,批内RSD为2.0%~6.1%,批间RSD为3.3%~7.6%。     

液相色谱-串联质谱法测定花生中丙硫菌唑及其脱硫代谢物

建立了液相色谱-串联质谱(HPLC-MS/MS)同时检测花生中丙硫菌唑及其主要代谢物硫酮菌唑的方法.花生样品经乙腈提取后,用乙腈饱和的正己烷除掉脂类杂质,C18分散固相萃取净化样品.采用含有5 mmol/L乙酸铵、0.2％乙酸和乙腈作为流动相进行梯度洗脱,在电喷雾-多反应监测离子模式下进行定性与定量分析.丙硫菌唑和硫酮菌唑在2.0,4.0和20.0 μg/kg的添加浓度时回收率为87.22％～102.46％;相对标准偏差小于10.0％;方法定量限为2.0 μg/kg.     

基质分散固相萃取-高效液相色谱/串联质谱法检测红薯中氯吡脲

建立了分散固相萃取-高效液相色谱/串联质谱法测定红薯中氯吡脲含量的分析方法.样品经分散剂(硅胶,C18HC)研磨分散提取,甲醇洗脱.采用Thermo Hypersil Gold C18色谱柱(150×2,1 mm,5μm)分离,以甲醇(A)/0.1％甲酸-5 mmol/L甲酸铵(B)作为流动相,梯度洗脱,采用串联质谱在正离子扫描方式下,通过选择反应模式定量分析,外标法定量.氯吡脲在2.63～675.00 ng/mL范围内线性关系良好,相关系数R2＞0.999.定量检测限为0.66 ng/mL.氯吡脲在10、25、50 ng/g三个浓度水平的添加回收率在70％～130％之间.该方法操作简单、准确,适用于红薯中氯吡脲的定量检测.     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.