选择离子流动管质谱法测定大蒜酶解液顶空中17种有机硫化合物

采用选择离子流动管质谱(SIFT-MS)法,顶空取样后,以H3O+,NO+或O2+为初始离子,定量分析了17种大蒜酶解液挥发性有机硫化合物。结果表明:有机硫化合物主要为二烯丙基硫醚、甲基烯丙基硫醚、硫代亚磺酸酯和硫醇,其中二烯丙基二硫醚浓度为137 g/m3,二烯丙基三硫醚浓度为13.4 g/m3,甲基烯丙基二硫醚浓度为8.98 g/m3,它们分别占17种有机硫化合物总含量的77.3%,7.58%和5.08%(相对含量);本研究采用顶空取样方法测出大蒜素的浓度为5.63 g/m3,相对含量为3.20%。     

气相色谱-硫化学发光检测器法测定车用汽油中6种硫醚

采用气相色谱测定车用汽油中6种硫醚的含量。用DB-1毛细管色谱柱(60 m×0.32mm,0.50μm)分离和硫化学发光检测器检测。6种硫醚的质量浓度均在0.5~150mg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.03~0.26mg·kg-1之间。方法用于车用汽油的分析,加标回收率在76.6%~120%之间,测定值的相对标准偏差(n=7)在0.50%~6.4%之间。     

QuEChERS-超高效液相色谱-串联质谱法同时测定保健食品中21种非法添加化学药物

建立了QuEChERS-超高效液相色谱-串联质谱测定改善睡眠类和提高免疫力类保健食品中21种非法添加化学药物的分析方法。口服液、保健酒分别用乙腈和乙腈-水-甲酸(60∶39∶1,v/v/v)振荡提取,QuEChERS法净化;采用Acquity UPLCTMBEH C18色谱柱(50 mm×2.1 mm,1.7μm)分离,以乙腈和2 mmol/L乙酸铵溶液(含0.1%(v/v)甲酸)为流动相进行梯度洗脱;在电喷雾离子源正离子模式(ESI+)下电离,多反应监测(MRM)模式检测。结果表明,21种化学药物在1~100μg/L范围内线性关系良好,相关系数(R2)均≥0.992,检出限(LOD)为0.07~3.41μg/kg,定量限(LOQ)为0.22~11.36μg/kg。3种加标水平(10、20和100μg/kg)下,21种化学药物在口服液和保健酒中的平均加标回收率分别为61.4%~116.5%和67.4%~98.4%;相对标准偏差(RSD)分别为0.2%~13.4%和0.2%~11.8%。该法简便,灵敏性高,实用性强,可用于改善睡眠和提高免疫力类保健食品中21种非法添加化学药物的检测。     

气相色谱-质谱法检测涂料中4种苯并三唑类紫外线吸收剂

采用气相色谱-质谱技术对涂料中4种高关注苯并三唑类紫外线吸收剂的含量进行测定。样品风干成膜后以正己烷或乙腈为溶剂进行超声提取,DB-5MS色谱柱(30 m×0.25 mm×0.25μm)分离,SCAN模式进行分析检测。4种苯并三唑类紫外线吸收剂质量浓度在0.5~50μg/m L范围内与峰面积呈线性关系。方法定量下限(S/N=10)为10 mg/kg。加标回收率为84.3%~100.4%,相对标准偏差(RSD,n=6)不大于8.9%。方法适用于涂料中高关注苯并三唑类紫外线吸收剂的日常分析检测。     

气相色谱法测定黄芪饮片中有机氯类农药残留

采用气相色谱电子捕获检测器(ECD)测定黄芪饮片中9种有机氯类农药残留。黄芪饮片样品以丙酮、二氯甲烷提取,浓硫酸磺化,采用HP–5(30 m×0.32 mm,0.25μm)色谱柱,气化室温度为250℃,检测器温度为300℃。以标准曲线法计算农药含量,加标回收率为94.5%~104.4%,测定结果的相对标准偏差为1.7%~2.7%,检出限为0.061~0.175 ng/m L。该方法简单、快速、稳定、可靠,可用于黄芪饮片中9种有机氯类农药残留的测定。     

液相色谱-串联质谱法快速测定电子电气产品中全氟辛酸和全氟辛烷磺酸

建立了液相色谱-串联质谱法快速测定电子电气产品中全氟辛酸(PFOA)和全氟辛烷磺酸(PFOS)的分析方法。采用加速溶剂萃取提取样品中PFOA和PFOS,二氯甲烷作溶剂,外标法定量,LC-MS/MS分析时间1 m in。电子电气产品中PFOS不同加标质量分数(0.25,0.75和1.25 mg/kg)的平均回收率分别为:91.6%、92.8%和94.7%;PFOA不同加标质量分数(0.50,1.25和2.25 mg/kg)的平均回收率分别为:90.1%、91.5%和93.4%;PFOS和PFOA测定的相对标准偏差分别为2.8%~3.3%和4.2%~4.9%。测定了金属框架涂层和氟聚合物材料中PFOS和PFOA的含量,PFOS含量分别为16μg/m2和0.89%,PFOA未检出     

双波长UPLC同时测定桃金娘根中没食子酸和鞣花酸

建立了超高效液相色谱(UPLC)结合二极管阵列检测器(PDA)同时测定桃金娘根中没食子酸和鞣花酸的方法。样品经过甲醇超声提取,过滤,蒸干甲醇,残渣用二甲基亚砜定容。采用Waters BEH C18色谱柱(2.1×100 mm1.7μm),以乙腈-0.2%H2PO4溶液为流动相进行梯度洗脱,流速0.25 m L/min,检测波长为271 nm和253 nm。没食子酸在0.686~68.600μg/m L,鞣花酸在0.504~50.373μg/m L浓度范围内呈良好线性关系,相关系数分别为0.9999,0.9999;样品加标平均回收率分别为97.2%~99.0%、96.2%~98.9%;没食子酸和鞣花酸峰面积的RSD分别为1.1%和1.9%,迁移时间RSD为0.9%和1.3%;检出限分别为0.45和0.23 ng/m L。     

超高效液相色谱-Orbitrap高分辨质谱用于减肥和壮阳类保健食品中32种非法添加药物的快速筛查和确证北大核心CSCD

建立了基于超高效液相色谱-Orbitrap高分辨质谱的快速筛查及确证减肥和壮阳类保健食品中32种非法添加药物的分析方法,并总结了数据库建立和应用的相关要点。研究对象聚焦于非法添加药物的衍生物,在对比正负离子模式下各化合物响应强度的基础上建立了高分辨质谱信息库,对提取溶剂、色谱柱温度等实验条件进行了详细探究,尽可能给出了较宽的标准曲线线性范围。使用Hypersil gold vanquish色谱柱(100 mm×2.1 mm,1.9μm),梯度洗脱,流量0.3 mL/min,正、负离子全扫描/数据依赖的二级扫描模式,在17 min内完成32种目标化合物的数据采集,通过TraceFinder软件进行快速定性筛查和定量。结果显示在17 min内32种化合物能得到较好分离;2种基质加标溶液中32种化合物的一级质谱离子精确质量数的实测值与理论值均在5×10^(-6)误差之内,二级碎片离子质量数的实测值与理论值均在1×10^(-5)误差之内;方法学验证结果表明,所有化合物均显示出优异的线性关系,相关系数(r^(2))均大于0.99;固体基质中除达泊西汀、羟基硫代豪莫西地那非、硫代豪莫西地那非、硫代西地那非、去甲基硫代西地那非的回收率较低外,其余27种化合物的回收率为50.5%~84.5%,相对标准偏差(RSD)为1.2%~13%,液体基质中32种化合物的回收率范围为60.4%~109.3%,RSD为0.77%~8.2%;在48份减肥及壮阳类保健食品中检出1份阳性样品,检出率2.08%。该方法操作简单,结果定性准确,可用于减肥及壮阳类保健食品中32种非法添加药物的快速筛查及确证。     

大蒜素的检测及大蒜辣素分解机理的探讨

通过正交试验方法,研究了硫酸钡吸光比浊法测定大蒜中大蒜素含量的最佳实验条件。在选定实验条件下,体系的吸光度与硫酸根离子浓度呈线性关系,相关系数r为0.9985,相对标准偏差(RSD)为0.86%。采用高效液相色谱法对样品中二烯丙基二硫醚进行定量检测,其检测结果与吸光比浊法的结果具有一定的互补对照性。在此基础上采用红外光谱法、气相色谱-质谱法对大蒜素中含硫活性成分进行定性分析,并将四种方法结果进行对比,对大蒜辣素过热分解的机理进行了探讨,为大蒜素中不同含硫化合物之间的转化提供了依据。     

保健食品中9种镇静催眠类药品的UPLC-MS/MS法检测及质谱裂解特征的研究

建立了同时测定保健食品中9种镇静催眠类化合物(氯美扎酮、三唑仑、阿普唑仑、艾司唑仑、地西泮、硝西泮、奥沙西泮、劳拉西泮、氯氮卓)的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法,并研究了其质谱裂解规律。样品以甲醇为提取溶剂,经Zorbax SB-C18(3.5μm,2.1 mm×150 mm)色谱柱分离,乙腈-水(含0.1%甲酸)为流动相梯度洗脱,流速为0.3 m L/min。采用电喷雾离子源(ESI),正离子多反应监测(MRM)扫描方式检测,基质匹配标准曲线法定量。9种药物在0.5~50μg/L范围内线性关系良好,相关系数(r2)均大于0.99,定量下限为1.6~9.2μg·kg~(-1)。低、中、高3个加标水平下的平均回收率为78.1%~101.2%,日内相对标准偏差(RSD)为1.4%~9.7%,日间RSD为2.0%~11.2%。该法简便、快速、准确可靠,适合于保健食品中非法添加镇静催眠类药品的高通量筛查。而对目标化合物碎片离子及质谱裂解规律的研究,也为其定性鉴别和定量分析提供了参考。     

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%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.     

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.