气相色谱/质谱分析烟草中的主要生物碱

用毛细管气相色谱法测定烟草中烟碱、降烟碱、麦斯明、二烯烟碱、新烟碱、去氢新烟碱、2,3′-联二吡啶、可替宁8种主要生物碱的方法。烟草样品经二氯甲烷/甲醇(V/V,3∶1)萃取,过一次性滤膜,进样,经DB-5MS毛细管柱分离,由气相色谱-氢火焰离子化检测器(FID)检测定量,质谱定性。该方法操作简单,重现性好,回收率较高。8种生物碱相对标准偏差为2.59%~7.07%;回收率为89.4%~98.7%。     

全扫描-选择离子数据采集技术应用于烟草中生物碱的快速测定

建立了应用气相色谱-质谱(GC-MS)全扫描-选择离子监测(Scan-SIM)数据采集方式同时测定烟草中8种含量相差较大的生物碱的方法,采用Scan模式分析烟碱、降烟碱、新烟碱、去氢新烟碱,同时采用SIM模式分析麦斯明、二烯烟碱、2,3′-联吡啶、可铁宁。结果表明,烟草中各生物碱的回收率为94.8%～98.8%,5次测定的相对标准偏差均小于6%。该方法具有简单、快速、准确的特点,应用于烟草样品测定,结果令人满意。     

GC/MS-SIM测定烟草中的生物碱

为了同时分析烟草中的烟碱和微量生物碱,考察了提取剂、提取时间、料液比对生物碱提取率的影响,建立了烟草中主要生物碱GC/MS-SIM快速测定方法,并采用这种方法分析了云南不同品种烤烟(C3F)中的生物碱。结果表明:该方法前处理简单,分析时间短,重复性好。烟草中的烟碱、降烟碱、麦斯明、二烯烟碱、新烟碱、去氢新烟碱、2,3’-联吡啶、可替宁能够完全分离。因此GC/MS-SIM适合批量烟叶样品中生物碱的分析。     

超高效液相色谱-串联质谱法快速分析烟叶中的8种生物碱

采用超高效液相色谱-串联质谱(UPLC-MS-MS)建立了快速分析烟叶中8种生物碱的分析方法。50 mg烟叶粉末样品经2 mL 6%氨水浸润后，以10 mL二氯甲烷超声提取20 min,有机相用N-丙基-乙二胺(PSA)净化后氮吹近干，再以乙腈超声复溶后用UPLC-MS-MS分析。烟叶中8种生物碱(烟碱、新烟碱、新烟草碱、降烟碱、二烯烟碱、2,3′-联吡啶、可替宁、麦斯明)的平均回收率在86.5%～102%之间，相对标准偏差(n=6)为2.1%～5.4%;方法对烟碱的检出限为0.45 mg/g,定量限为1.5 mg/g;对其余7种微量生物碱的检出限在0.15～0.6μg/g之间，定量限在0.5～2μg/g之间。本方法适用于烟叶中8种生物碱含量的快速测定。     

加速溶剂萃取-气相色谱-串联质谱法检测烟草中生物碱

建立了气相色谱-串联质谱(GC-MS/MS)法同时测定烟草中烟碱、降烟碱、麦斯明、假木贼碱和新烟草碱等5种生物碱的分析方法。以甲醇和Na OH溶液混合溶剂作提取溶剂,样品经加速溶剂萃取(ASE)萃取后,利用GC-MS/M S的多反应监测模式(M RM)测定,内标法定量。5种生物碱的检出限在0.06~0.12μg/m L之间,加标回收率介于88.9%~106.8%,相对标准偏差(RSD)均小于6%。方法适用于批量烟草样品中生物碱的快速测定。     

反相离子对高效液相色谱法同时测定头发中的尼古丁和可天宁

尼古丁(nicotine),又称烟碱,是烟草及其制品中含量最丰富的生物碱,会导致吸烟成瘾;可天宁(cotinine)是尼古丁在人体代谢过程中的主要产物。尼古丁和可天宁分布于人体头发和体液中,作为重要的生物标记物,常用以衡量烟草对人体健康的影响程度,受到生物医学、环境科学及烟草健康研     

超声波辅助提取-高效液相色谱法测定烟草废弃物中烟碱的含量

<正>烟碱又称尼古丁,是烟草属经济作物中的主要生物碱,约占烟草中所有生物碱的95%以上^[1]。我国作为烟草大国,每年的烟草产量十分可观,烟草的大量生产必然造成烟草废弃物的大量堆积。据统计,2015-2019年,我国有效烟草年均产量约210万t, 其中有约25%废次烟叶、烟杆、烟茎等遭到废弃^[2-3]。烟草废弃物中可提取利用的有效物质主要有烟碱、茄尼醇、纤维素、木质素、植物蛋白等,它们可被用来制取烟酸,进而制取烟酰胺^[4-5]。其中,     

热脱附-冷阱系统-气相色谱-质谱法同时测定卷烟烟丝中7种生物碱和9种香精成分

建立了热脱附-冷阱系统-质谱技术(TDU-CIS-MS)同时检测卷烟烟丝中7种生物碱(尼古丁、降烟碱、新烟碱、麦斯明、二烯烟碱、异喹啉和2,3-联吡啶)和9种香精(二氢香豆素、香兰素、香豆素、乙基香兰素、甲基香兰素、7-甲基香豆素、7-甲氧基香豆素、7-乙氧基-4甲基香豆素和环香豆素)的分析方法.通过在线热脱附卷烟样品...     

基于ISFET的尼古丁传感器的研究

报道了一种测定尼古丁的新方法。用二苦胺作电活性物质 ,将离子敏感场效应晶体管与药物敏感膜相结合 ,制成尼古丁传感器 ,测定尼古丁的线性范围为 1 .0×1 0 - 2 ～ 3.0× 1 0 - 5mol/L,适宜的 p H值范围为 5 .0～ 8.5 ,传感器灵敏度为 5 8.0 m V/pc。用该传感器分析烟草中的尼古丁含量 ,结果和分光光度法一致     

毛细管电泳-电致化学发光联用技术检测烟草中尼古丁含量

建立了毛细管电泳-电致化学发光联用技术(CE-ECL)检测烟草浸出液中尼古丁含量的方法。考察了检测电位、检测池中Ru(bpy)32+浓度和缓冲液pH值、CE运行缓冲液浓度和pH值、进样时间和电压,以及CE分离电压等实验条件对尼古丁测定的影响。在优化的条件下,尼古丁检测的线性范围为低浓度段:1～100μg/L(r>0.999)、高浓度段:100～1500μg/L(r>0.996),检出限为0.5μg/L(S/N=3)。将本方法用于3种品牌的烟草浸出液中尼古丁含量的测量,测定值均与烟盒上尼古丁的标注值相吻合,样品的加标回收率为95%～106%。     

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.