同位素稀释-气相色谱-质谱法测定白酒中23种邻苯二甲酸酯类化合物

提出了同位素稀释-气相色谱-质谱法测定白酒中23种邻苯二甲酸酯类化合物含量的方法。样品用正己烷-乙酸乙酯(1+1)混合液提取后,经DB-5MS毛细管色谱柱分离,采用电子轰击离子源选择离子反应监测模式进行质谱测定,同位素内标法进行定量分析。23种邻苯二甲酸酯类化合物的线性范围在0.2~3.0mg·L-1之间,测定下限(10S/N)在0.05~0.1mg·kg-1之间。加标回收率在73.2%~122%之间,相对标准偏差(n=6)在0.49%~11%之间。     

气相色谱-质谱法测定烟用香精香料中香兰素和乙基香兰素

采用气相色谱-质谱法测定烟用香精香料中香兰素和乙基香兰素的含量。烟用香精香料样品与萃取剂的比例为1g比100mL,在500W下超声萃取10min。在气相色谱分离中用DBWAXETR毛细管柱为固定相,在质谱分析中采用选择离子监测模式。以丙酸苯乙酯为内标物。香兰素和乙基香兰素的线性范围均为0.5~200mg·L-1,检出限(3S/N)分别为0.03,0.02mg·kg-1。加标回收率在91.4%~109%之间,测定值的日内相对标准偏差(n=5)在0.43%~2.2%之间,日间相对标准偏差(n=5)在0.67%~2.6%之间。     

固相萃取-气相色谱-质谱法同时测定植物油中7种邻苯二甲酸酯

采用气相色谱-质谱法测定植物油中7种邻苯二甲酸酯类增塑剂的含量。样品用正己烷溶解后,经Cleanert PAE固相萃取柱净化,采用正己烷-乙酸乙酯(1+1)混合溶液洗脱,洗脱液用氮气吹至近干,乙腈定容后,在DB-5毛细管色谱柱上分离,质谱中选择电子轰击离子源-选择离子监测模式。7种邻苯二甲酸酯的质量浓度在0.1~5.0 mg·L-1范围内呈线性,检出限(3S/N)为0.02 mg·kg-1。加标回收率在80.0%~120%之间,测定值的相对标准偏差(n=6)在1.1%~5.4%之间。     

气相色谱-质谱法测定洗涤用品中6种邻苯二甲酸酯

建立了测定洗涤用品中6种邻苯二甲酸酯的气相色谱-质谱法。样品经乙酸乙酯超声提取5min,提取液在HP-5MS毛细管色谱柱上分离,质谱分析中采用电子轰击离子源和选择离子监测模式,外标法定量。6种邻苯二甲酸酯的线性范围为1.0~20mg·L~(-1),方法的检出限(3S/N)均小于1.0mg·kg~(-1);样品中6种邻苯二甲酸酯的加标回收率在85.6%~113%之间,测定值的相对标准偏差(n=6)在2.2%~5.8%之间。     

气相色谱-质谱法测定再造烟叶中甲酰胺

再造烟叶样品用甲醇提取5min,取上层清液,经有机相滤膜过滤,采用气相色谱-质谱法测定滤液中甲酰胺的含量。在气相色谱分离中采用DB-Wax毛细管色谱柱(0.32mm×30m,0.25μm),在质谱分析中采用选择离子监测模式。甲酰胺的质量浓度在0.1~5.0mg·L^-1内与其对应的峰面积呈线性关系,检出限(3S/N)为0.01mg·L^-1。加标回收率为92.5%~105%,测定值的日内相对标准偏差(n=6)为2.5%~3.0%,日间相对标准偏差(n=3)为4.4%。     

GC-MS法测定白酒中邻苯二甲酸酯残留量

采用正己烷提取白酒中的16种邻苯二甲酸酯类增塑剂,建立了气相色谱-质谱联用法测定白酒中污染物邻苯二甲酸酯类增塑剂残留量的检测方法。该方法对白酒中16种邻苯二甲酸酯化合物的检测限为0.05 mg/kg,方法的检测浓度线性范围为0.5~5.0 mg/L,样品的加标回收率为80.0%~95.0%,测定结果的相对标准偏差为2.1%~7.0%(n=6)。该方法可以满足白酒中污染物邻苯二甲酸酯检测的需要。     

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。     

气相色谱-串联质谱法测定蔬菜和土壤中17种邻苯二甲酸酯

采用气相色谱-串联质谱法测定蔬菜和土壤中17种邻苯二甲酸酯的含量。蔬菜样品用乙腈均质提取,土壤利用水和乙腈振荡提取。在气相色谱分离中用DB-1701MS色谱柱为固定相,在质谱分析中采用多反应监测模式。17种邻苯二甲酸酯的质量浓度均在2.00~500μg·L-1范围内与其峰面积呈线性关系,测定下限(10S/N)在0.01~0.32μg·kg-1之间。以空白样品为基体进行加标回收试验,所得回收率在71.1%~118%之间,测定值的相对标准偏差(n=6)在0.20%~15%之间。     

顶空-气相色谱-质谱法测定地表水和废水中55种挥发性有机物含量

采用顶空-气相色谱-质谱法测定地表水和废水中55种挥发性有机物的含量。选择顶空平衡温度和时间分别为65℃和50min。在气相色谱分离中用DB-624色谱柱为固定相,在质谱分析中采用全扫描和选择离子监测模式。以氟苯和1,2-二氯苯-D4为内标物。55种挥发性有机物的线性范围均为10.0~400μg·L-1。全扫描模式下,检出限在0.8~6.8μg·L-1之间,加标回收率在81.3%~116%之间,测定值的相对标准偏差(n=6)在0.40%~15%之间。在选择离子监测模式下,检出限在0.2~1.1μg·L-1之间,加标回收率在81.0%~117%之间,测定值的相对标准偏差(n=6)在0.40%~6.5%之间。     

气相色谱-质谱法测定三七提取物中16种多环芳烃

提出了气相色谱-质谱法测定三七提取物中16种多环芳烃。样品用环己烷萃取,经凝胶渗透色谱净化处理后,采用HP-5MS色谱柱分离,电子轰击离子源-选择离子检测模式检测,外标法定量。16种多环芳烃的质量浓度在0.01~1.0mg·L-1范围内与其峰面积呈线性关系,方法的测定下限(10S/N)在0.3~9.5μg·kg-1之间。在0.01,0.05,0.1mg·kg-1添加水平下,16种多环芳烃的加标回收率在70.1%~111%之间,相对标准偏差(n=6)在3.0%~9.4%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.     

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.     

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.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.