超高效液相色谱-高分辨四级杆飞行时间质谱法快速筛查乳制品中磺胺类与氟喹诺酮类药物

利用超高效液相色谱-高分辨四级杆飞行时间质谱联用技术,建立了一种快速筛查乳制品中8种氟喹诺酮5种磺胺类药物及其4种乙酰化代谢物的新方法。采用乙腈-20%三氯乙酸溶液(100∶1,V/V,pH 2.0)作溶剂和Oasis HLB固相萃取载体作吸附剂,实现了牛奶样品中17种目标物的同时提取和有效净化。利用MassLynx Chromlynx软件建立了这17种分析物的数据库。以Full Scan/MSE进行定性筛查和定量检测。4种代谢物在10~2000μg/L范围内和其它分析物在0.5~100μg/L范围内,其基质匹配内标校准曲线呈现良好的线性(R2>0.983)。氟喹诺酮的定量限为0.5~0.8μg/kg,磺胺类药物及代谢物的定量限为0.5~13.0μg/kg。在3个添加水平分析物的平均回收率(69%~92%)在职业分析化学家协会(AOAC)提出的允许范围之内,相对标准偏差均小于15%。本方法快速而灵敏,成功用于乳制品中抗生素及其代谢物的筛查、确认和定量分析。所研究的每种药物及代谢物残留均低于有关的最高残留限量(MRLs),但某些乳制品中其总残留量已超过最高残留限量。     

QuEChERS-超高效液相色谱-串联质谱法测定云南野生菌中甲拌磷及其代谢物

建立了云南野生菌中甲拌磷及其代谢物残留量的QuEChERS-超高效液相色谱-串联质谱测定方法。野生菌样品经1%HAc-乙腈提取后,利用PSA填料净化,过滤膜后分析,正离子多反应监测模式检测,外标法定量。甲拌磷及其代谢物在0.05~5.0μg/L浓度范围内具有较好线性关系,检出限范围为0.008~0.08μg/kg,定量限范围为0.03~0.30μg/kg。在3个加标浓度下,平均回收率范围为73.3%~98.5%,相对标准偏差范围为4.4%~9.9%。该方法能够满足云南野生菌中甲拌磷及其代谢物残留分析的要求。     

固相萃取-高效液相色谱-串联质谱法测定畜禽粪便中的残留抗生素

建立了固相萃取-高效液相色谱-串联质谱法(HPLC-MS/MS)同时测定畜禽粪便中四环素类化合物(四环素、金霉素、土霉素)、喹诺酮类化合物(诺氟沙星、环丙沙星、洛美沙星)和磺胺二甲嘧啶7种抗生素的检测方法。样品中的抗生素用含有甲醇、乙酸和水(6:3:1, 体积比)的混合溶液提取后,经HLB固相萃取小柱纯化富集,采用Symmetry C₁₈色谱柱分离,0.3%甲酸水溶液和0.3%甲酸乙腈溶液作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,外标法定量。结果表明,四环素类化合物和喹诺酮类化合物在50~1000 μg/L、磺胺二甲嘧啶在5~100 μg/L的范围内具有良好线性。3倍信噪比下,四环素类化合物、喹诺酮类化合物和磺胺二甲嘧啶的检出限分别为0.25~7.18、0.15~3.16和0.04 μg/kg。在猪粪和鸡粪样品中添加0.1~10 μg/g水平的四环素类化合物、喹诺酮类化合物和磺胺二甲嘧啶,其平均添加回收率为40%~124%,相对标准偏差(RSD)为3.0%~9.5%。采用该方法对部分养殖场的猪粪和鸡粪进行了检测,结果表明,四环素类化合物均有不同程度的检出,喹诺酮类化合物和磺胺二甲嘧啶有部分检出。该方法具有灵敏度和准确度高的特点,可满足畜禽粪便中四环素类化合物、喹诺酮类化合物及磺胺二甲嘧啶的检测。     

气相色谱-火焰光度法测定水产品中敌敌畏残留

本文建立了快速、准确测定水产品中敌敌畏残留量的气相色谱-火焰光度检测法(GC-FPD)。样品经过乙腈涡旋振荡-固液萃取,乙腈和饱和正己烷组成的溶液中去除类脂,乙酸乙酯反萃取净化,定容后采用气相色谱分析。结果显示,在敌敌畏浓度为0~1.0μg·mL-1范围内,色谱峰的峰高与其浓度线性关系良好,相关系数(r2)为0.9996;在添加水平分别为2、4、20μg·kg-1的草鱼、虾和鳖空白肌肉组织样品中,加标回收率在87.9%~95.6%之间,相对标准偏差低于8%,检测限和定量限分别为0.6μg·kg-1和1.8μg·kg-1。     

气相色谱-负化学电离离子化-质谱法测定出口泥鳅中的硫丹及其代谢物

提出了快速检测出口泥鳅中硫丹及其代谢物硫丹硫酸盐的气相色谱-负化学电离离子化-质谱法。考察了快速溶剂萃取法、均质提取法和振荡提取法对试验效果的影响。通过固相萃取辅以冷冻离心的净化方法有效解决了油脂对硫丹及其代谢物测定的干扰问题。通过优化仪器条件,有效缩短了检测时间。硫丹及其代谢物的线性范围为0.005~0.400 mg·L-1,检出限在0.04~0.05μg·kg-1之间,测定下限在0.12~0.18μg·kg-1之间。对空白泥鳅样品进行加标回收试验,回收率在89.1%~100%之间,测定值的相对标准偏差(n=6)在2.9%~8.3%之间。本方法适用于出口泥鳅快速批量检测。     

超高效液相色谱-串联质谱法同时测定畜禽排泄物中20种磺胺类药物的残留

建立了超高效液相色谱-串联质谱(UPLC-MS/MS)同时测定畜禽排泄物中20种磺胺类药物残留量的分析方法。样品经冷冻干燥后粉碎过筛,90%酸化乙腈提取,HLB固相萃取柱净化,UPLC-MS/MS检测,基质匹配校准外标法定量。结果显示,20种磺胺类药物在2～250 ng/mL浓度范围内,线性良好,相关系数均>0.99,检出限为2μg/kg,定量限为5μg/kg。在添加浓度分别为5、10、500μg/kg时,平均回收率为78.0%～117%,相对标准偏差(n=6)为1.1%～14.2%。该方法具有较低的检出限、定量限及较高的回收率和稳定性,可应用于畜禽排泄物中20种磺胺类药物残留量的监测。     

固相萃取-高效液相色谱法同时检测畜禽粪便中14种兽药抗生素

研究并优化了同时分析畜禽粪便中14种抗生素(四环素、磺胺、氟喹诺酮和大环内酯类)的加速溶剂萃取参数、固相富集净化程序、以及高效液相色谱分离和检测条件。结果表明,以1%乙酸(pH 2.6)作为流动相,在270 nm的检测波长下,14种抗生素能达到基线分离。3倍信噪比下,四环素、磺胺、氟喹诺酮和大环内酯类抗生素的检出限分别为35～90μg/kg,12～28μg/kg,9～17μg/kg及19μg/kg。加标浓度在1和10μg/g时,畜禽粪便样品经过50%甲醇的柠檬酸盐缓冲溶液提取,HLB固相萃取柱富集净化后,四环素、磺胺、氟喹诺酮和大环内酯类抗生素的回收率分别达到了58%～75%和66%～83%,74%～93%和91%～101%,74%～80%和80%～88%,85%和68%,相对标准偏差分别为6.2%～10.7%和7.8%～13.6,2.6%～10.2%和4.4%～13.2%,6.1%～12.5%和8.3%～14.6%,10.6%和12.3%。采用此方法对辽宁省部分规模化养殖场的猪粪、牛粪和鸡粪样品进行了检测。4类抗生素都有检出,浓度范围分别为0.75～22.34 mg/kg,0.10～1.71 mg/kg,0.38～4.46 mg/kg和0.23～0.35 mg/kg。     

超高压液相色谱-串联质谱法测定畜禽粪便中3种β-受体激动剂残留

建立了畜禽粪便中3种β-受体激动剂药物残留的超高压液相色谱-串联四极杆质谱联用仪测定方法。样品酶解后经高氯酸溶液净化,调节p H值至碱性,乙酸乙酯提取,净化浓缩后以流动相定容,用超高压液相色谱-质谱联用仪检测,内标法定量。3种β-受体激动剂在0.5~20.0μg/L范围内线性关系良好,相关系数均大于0.998。畜禽粪便中3种β-受体激动剂的加标回收率为80.3%~110.2%,相对标准偏差为3.0%~7.7%,检出限(S/N=3)为0.04~0.07μg/kg。     

QuEChERS-超高效液相色谱-串联质谱法快速测定鱼肉中22种磺胺类药物残留

结合QuEChERS前处理技术,提出了测定鱼肉中22种磺胺类残留的超高效液相色谱-串联质谱法。样品用含0.1%(体积分数,下同)甲酸的乙腈溶液提取后,经QuEChERS试剂盒净化。净化液在Agilent ZORBAX Eclipse Plus C18色谱柱上分离,以0.1%甲酸溶液-甲醇为流动相进行梯度洗脱。采用电喷雾正离子源及计划式多反应监测模式进行测定,以内标法定量。磺胺硝苯、磺胺、磺胺喹噁啉的线性范围为0.5~50μg·L-1,检出限(3S/N)为0.5μg·L-1;其他19种磺胺类兽药的线性范围为0.1~50μg·L-1,检出限(3S/N)为0.1μg·L-1。加标回收率在78.2%~118%之间,测定值的相对标准偏差(n=6)在3.4%~19%之间。方法用于鱼肉中多种磺胺类药物残留的快速测定,结果与标准方法测定结果一致。     

超高效液相色谱-串联质谱法测定水产品中孔雀石绿及其代谢物残留量

采用超高效液相色谱-串联质谱法测定水产品中孔雀石绿及其代谢物的残留量。样品经盐酸羟胺、对甲苯磺酸、乙酸铵的混合液作为提取剂均质提取,乙腈萃取,并通过-18℃冷冻离心分层。以ACQUITY UPLC BEH C18色谱柱分离,用乙腈与5mmol·L-1乙酸铵溶液(75+25)的混合液洗脱,采用正离子模式监测。以氘代孔雀石绿和氘代隐色孔雀石绿为内标物。孔雀石绿和隐色孔雀石绿的线性范围均为1.0~20.0μg·L-1,检出限(3S/N)依次为0.05,0.06μg·kg-1。在1.0,2.0,5.0μg·kg-1等3个浓度水平进行加标回收试验,回收率在90.2%~106%之间,测定值的相对标准偏差(n=6)在2.1%~11%之间。     

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.