气相色谱-质谱法测定卷烟烟气总粒相物中14种芳香胺

以五氟丙酸酐为衍生化试剂,氘代2-氨基萘和氘代邻甲苯胺为双内标,采用DB-35MS石英毛细管柱(30 m×0.25 mm i.d×0.25 μm d.f)和选择离子模式,建立了卷烟烟气总粒相物中芳香胺的气相色谱-质谱分析方法.该方法检出限在0.03～2.13 ng/cig.之间,加标平均回收率在92.6%～110.4%之间,相对标准偏差在0.18%～6.4%之间.已用该方法测定了某品牌卷烟烟气总粒相物中14种芳香胺.     

离心破乳-气相色谱法测定黑米中残留抑霉唑的研究

报道了离心破乳-气相色谱法测定黑米中残留抑霉唑的方法. 考察了不同离心速率、不同离心时间的破乳效率. 试样以V(正己烷):V(乙酸乙酯)＝1:1提取, 经毛细管气相色谱柱HP-5 (30 m×0.25 mm×0.25 μm)分离, μ-ECD检测器测定. 方法检出限为1.0×10-3 mg/kg (S/N=3). 在添标水平0.05、 0.25和0.50 mg/kg时的平均回收率为92.3%～104.3%, 相对标准偏差为6.9%～9.3%. 线性范围为0.02～1.0 mg/L (r2=0.9994). 方法适合黑米中残留抑霉唑的测定.     

衍生化反应-气相色谱法测定聚氨酯胶黏剂中3,3′-二氯-4,4′-二氨基二苯基甲烷北大核心CSCD

采用衍生化反应-气相色谱法测定聚氨酯胶黏剂中3,3′-二氯-4,4′-二氨基二苯基甲烷(MOCA)的含量。聚氨酯胶黏剂样品0.500g用20mL甲苯超声萃取40min,在离心后的上层清液10mL中加入10.0mg·L^(-1 )3,3′-二氯联苯胺溶液10μL和N-甲基双三氟乙酰胺(衍生化试剂)20μL。用DB-5色谱柱(30m×0.25mm,0.25μm)分离,电子捕获检测器检测。以3,3′-二氯联苯胺为内标物。MOCA的线性范围为0.10~5.00mg·L^(-1),检出限(3S/N)为1.50mg·kg^(-1)。加标回收率为85.4%~96.7%,测定值的相对标准偏差(n=6)均小于2.0%。     

衍生化反应-气相色谱法测定聚氨酯胶黏剂中3,3′-二氯-4,4′-二氨基二苯基甲烷

采用衍生化反应-气相色谱法测定聚氨酯胶黏剂中3,3′-二氯-4,4′-二氨基二苯基甲烷(MOCA)的含量。聚氨酯胶黏剂样品0.500g用20mL甲苯超声萃取40min,在离心后的上层清液10mL中加入10.0mg·L~(-1 )3,3′-二氯联苯胺溶液10μL和N-甲基双三氟乙酰胺(衍生化试剂)20μL。用DB-5色谱柱(30m×0.25mm,0.25μm)分离,电子捕获检测器检测。以3,3′-二氯联苯胺为内标物。MOCA的线性范围为0.10~5.00mg·L~(-1),检出限(3S/N)为1.50mg·kg~(-1)。加标回收率为85.4%~96.7%,测定值的相对标准偏差(n=6)均小于2.0%。     

硅烷化GC/MS法同时测定卷烟中的糖、1,2-丙二醇和甘油

建立了硅烷化衍生化法结合气相色谱/质谱(GC/MS)法同时测定卷烟中1,2-丙二醇、甘油和糖类物质含量的分析方法。样品以N,N-二甲基甲酰胺(DMF)和N,O-双(三甲基硅烷基)三氟乙酰胺(BSTFA)为提取溶剂和衍生化试剂,于70℃衍生化反应30 min,采用DB-5MS色谱柱(60 m×0.25 mm×0.25μm),用GC/MS分析测定1,2-丙二醇,甘油、果糖、葡萄糖和蔗糖的含量。方法线性关系良好,检出限为0.04~2.85 mg/g,定量限为0.13~9.51 mg/g,平均加标回收率为90.3%~114.4%,相对标准偏差小于9.1%。方法适合于卷烟样品中1,2-丙二醇、甘油和糖类物质的同时测定。     

衍生-气相色谱法测定水产品中的游离甲醛

建立了水产品中游离甲醛残留量的衍生-气相色谱快速检测方法,对衍生剂、抗干扰剂、萃取剂、色谱条件进行了研究.用HP-5 (30 m×0.32 mm i.d.,0.25 μm)毛细管色谱柱,程序升温,γ-ECD检测器,外标法定量.甲醛的检出限为0.05 mg/kg,在0.1～20.0 mg/L范围内,其线性相关系数R2=0.9994,标准偏差为0.041,在0.5、 1.5、 5.0 mg/kg 3个添加水平下回收率为89.6%～102.6%.3个实验室间的RSD为2.7%～4.4%.     

气相色谱法测定食品中12种有机酸

采用气相色谱法测定食品中12种有机酸的含量。采用硫酸-甲醇溶液对食品中12种有机酸进行衍生,优化的试验条件如下:(1)硫酸-甲醇溶液(衍生试剂)的体积分数为20%;(2)衍生温度为80℃;(3)衍生试剂的加入量为4.0mL;(4)衍生时间为60min;(5)萃取试剂为三氯甲烷。用Agilent HP-5毛细管色谱柱(30 m×0.32 mm,0.25μm)分离,氢火焰离子化检测器检测。12种有机酸的质量浓度均在一定范围内与其衍生产物的峰面积呈线性关系,方法的检出限(3S/N)为0.023~0.076mg·kg~(-1)。方法用于食品样品的分析,加标回收率为76.0%~107%,测定值的相对标准偏差(n=6)为1.5%~6.9%。     

加速溶剂萃取-气相色谱-质谱法测定固体废物中酚类化合物

提出了气相色谱-质谱法测定固体废物中12种酚类化合物残留量的方法。样品以丙酮-二氯甲烷(2+3)混合液为萃取剂,经加速溶剂萃取仪提取后,在K-D浓缩装置上浓缩至1 mL,经硅胶柱净化后,用丙酮-二氯甲烷(1+9)混合液淋洗后再经K-D浓缩至1 mL,通过HP-5 MS石英毛细管色谱柱(30 m×0.25 mm,0.25μm)分离,采用电子轰击离子源选择离子监测模式进行质谱测定。12种酚类化合物的检出限(3S/N)在9.60～18.5μg.kg-1之间。以空白土壤样品为基体进行回收试验,测得回收率在74.7%～108.4%之间,测定值的相对标准偏差(n=7)均小于7.5%。     

气相色谱-质谱法测定药品中克霉唑的含量

建立了气相色谱-质谱法测定药品中克霉唑含量的分析方法。采用DB-35 MS色谱柱(30 m×0.25 mm×0.25μm)进行分离,质谱以选择离子模式进行检测,同位素内标法定量。在优化的条件下,克霉唑在0.05～5.0μg/mL范围内呈良好的线性关系,相关系数为0.9997。样品加标平均回收率为91.1%～97.2%,相对标准偏差不大于6.5%。本方法简便、快速,灵敏度高、准确性好,可用于药品中克霉唑含量的测定。     

气相色谱-质谱联用法测定包装膜和包装袋中富马酸二甲酯残留量

提出了气相色谱-质谱联用法测定包装膜和包装袋中富马酸二甲酯残留量的方法。样品中富马酸二甲酯用乙酸乙酯萃取,经针式过滤头净化,采用HP-5MS毛细管色谱柱(30 m×0.25 mm,0.25μm)进行分离。采用气相色谱-质谱电子电离源和全扫描监测模式进行测定。富马酸二甲酯的质量浓度在0.5~100.0 mg.L-1浓度范围与其对应的峰面积呈线性关系,测定下限(10S/N)为0.1 mg.kg-1。在5.0,10.0,20.0,30.0,40.0,50.0 mg.kg-16个添加水平下,富马酸二甲酯的回收率在95.0%~102.5%之间,相对标准偏差(n=6)小于6%。     

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.     

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.     

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.     

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.     

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.     

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.     

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.