高效液相色谱法快速测定环境空气中13种醛酮类化合物

建立高效液相色谱法快速测定环境空气中13种醛酮类化合物的方法。选用Poroshell 120 SB–C_(18)色谱柱(250 mm×4.6 mm,4μm)为分离柱,以水–乙腈溶液为流动相,梯度洗脱,流量为1.5 mL/min,柱温为50℃,进样体积为10μL,采用紫外检测器检测,检测波长为360 nm。13种醛酮类化合物的质量浓度在0.05~2.0μg/mL范围内与色谱峰面积具有良好的线性关系,相关系数均不小于0.9998,方法检出限为0.16~0.47μg/m³。空白样品加标回收率为97.2%~101.1%,测定结果的相对标准偏差为0.5%~4.3%(n=6)。该方法分析速度快,准确度和灵敏度高,精密度好,适用于环境空气中醛酮类化合物的快速测定。     

环境空气中痕量硝基苯测定方法研究

建立了Tenax富集-气相色谱仪测定环境空气中痕量硝基苯的方法。用Tenax采样管吸附环境空气中的痕量硝基苯,用1.0mL石油醚淋洗解析吸附的硝基苯,用气相色谱-电子捕获检测器进行检测,外标法定量,线性相关系数为0.9992,平均回收率为95.9%～97.1%,RSD不大于5.2%(n=5)。按采样10L计算,检出限为0.0002mg/m3,经实际样品测定完全能满足环境空气中痕量硝基苯监测的要求。     

微波萃取/气质联用法测定细颗粒物(PM2.5)中邻苯二甲酸酯类化合物

建立了环境空气细颗粒物(PM2.5)中痕量邻苯二甲酸酯类化合物(PAEs)的微波萃取(ME)/气相色谱-质谱联用(GC-MS)分析方法。样品经乙酸乙酯-丙酮混合溶剂微波提取后,经DB-5MS色谱柱分离,采用SCAN/SIM模式进行质谱测定,外标法定量。结果显示,PAEs的线性范围为100~1 000 pg,方法的检出限为0.101~0.262 ng/m3,加标回收率81.6%~129%。将本方法应用于常州化工园区环境空气细颗粒物中PAEs的分析检测发现,大部分PAEs在样品中检出,其中邻苯二甲酸二异丁酯(DIBP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二辛酯(DEHP)检出浓度较高,方法能够满足环境空气细颗粒物中痕量PAEs的测定要求。     

气相色谱法同时测定环境空气中6种丙烯酸酯

建立气相色谱法同时测定环境空气中丙烯酸甲酯、丙烯酸乙酯、甲基丙烯酸甲酯、丙烯酸丙酯、丙烯酸丁酯和甲基丙烯酸丁酯6种丙烯酸酯化合物。采用活性炭吸附环境空气中的丙烯酸酯,然后用二氯甲烷解吸,选用DB-35色谱柱,采取程序升温方式,用带氢火焰离子化检测器的气相色谱仪检测。6种丙烯酸酯的质量浓度在2～80μg/mL范围内与色谱峰面积线性关系良好,相关系数均为0.999 9。当采样体积为20 L时,方法检出限为0.008～0.01 mg/m3。样品加标回收率为82.3%～104%,测定结果的相对标准偏差为1.1%～9.8%(n=6)。该方法样品处理简单,抗干扰,便于推广应用。     

气相色谱-质谱法测定有机建筑粘合剂中3种苯胺类化合物含量

提出了气相色谱-质谱法测定有机建筑粘合剂中3种苯胺类化合物含量的方法。样品中3种苯胺类化合物用乙醇超声提取,离心分离后,所得提取液过0.22μm有机滤膜,滤液供气相色谱-质谱分析。在气相色谱分离中用DB-WAX毛细管色谱柱(30m×0.25mm,0.25μm)为固定相,在质谱分析中采用全扫描和选择离子监测模式。3种苯胺类化合物在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.3~0.6mg·kg-1之间。在3个浓度水平上做回收试验,加标回收率在91.1%~97.3%之间,相对标准偏差(n=6)在1.7%~4.0%之间。     

气相色谱法测定水样中三唑磷残留量

用气相色谱法对水样中残留的三唑磷的含量进行测定.水样经苯提取,采用HP-5毛细管色谱柱(30 m×0.32 mm,0.25 μm)分离,用氮磷检测器测定.三唑磷的质量浓度在0.0051.0 mg·L-1范围内与其峰面积呈线性关系,检出限(3S/N)为3.5 μg·L-1.方法的回收率在94.0%～97.5%之间,测定结果的相对标准偏差(n=6)小于3.7%.     

气相色谱法测定驱蚊功效印刷品中3种功效化合物

建立了气相色谱–氢火焰离子技术测定功效印刷品中3种驱蚊成分的方法。样品用二氯甲烷进行超声提取,邻苯二甲酸二丁酯为内标,利用毛细管色谱柱HP–5(30 m×0.32 mm,0.25μm)分离,保留时间定性,内标法定量。结果表明,3种驱蚊功效物质色谱分离良好,在质量浓度0.1~1.0 mg/L范围内与色谱峰面积呈线性相关。方法定量限(10S/N)为1.25 mg/kg,样品加标回收率为97%~108%,测定结果的相对标准偏差不大于8.1%(n=6)。该方法快速、可靠、准确、简便,适用于驱蚊功效的印刷品中3种驱蚊功效类化合物的分析检测。     

丙丁梭菌萃取发酵产物的气相色谱分析

建立了3种溶剂中产物丙酮、乙醇、正丁醇的气相色谱分析方法。色谱条件为:DB-624色谱柱(30 m×0.32 mm,1.8μm)及FFAP色谱柱(30 m×0.32 mm,0.25μm),FID检测器,程序升温,氮气为载气。采用内标法定量,内标物为异丁醇,进样体积1μL。丙酮、乙醇、正丁醇的浓度与色谱峰面积线性相关,相关系数为0.997 43~0.999 97,测定结果的相对标准偏差为0.19%~2.01%(n=5),回收率为95.1%~101.2%。     

针式萃取-气相色谱联用测定加油站附近空气中苯系物

提出了气相色谱法测定加油站附近空气中苯系物(甲苯、乙苯、邻二甲苯和间,对二甲苯)含量的方法。采用针式萃取装置对样品中的苯系物进行收集和富集,然后经气相色谱热解吸,采用SE 30毛细管色谱柱(30m×0.25mm,0.33μm)进行分离,用氢火焰离子化检测器进行测定。方法的检出限(3S/N)在0.36～1.32μg之间。方法的回收率在94.1%～104.5%之间,相对标准偏差(n=5)在4.9%～8.7%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%。     

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.     

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.     

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.     

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.