低温富集/GC-MS分析南丰蜜桔果肉成分的方法研究

建立了低温富集/气相色谱-质谱测定南丰蜜桔果肉成分的方法。对样品前处理中的溶剂种类、冷冻温度以及冷冻时间进行了优化,最终确定低温富集的前处理条件:正己烷为萃取溶剂;冷冻温度为-40℃;冷冻时间选择1 h。结果表明,采用低温富集/GC-MS结合保留指数定性对南丰蜜桔果肉进行成分分析,共鉴别出64种主要成分,主要包括酯类、萜烯类、醇类以及烷烃类。将低温富集所得结果分别与常温液液萃取结果及文献结果进行比较,所建立的方法可选择性富集一些极性大、热稳定性较差、难挥发性的物质。     

低温富集液液萃取-气相色谱-串联质谱法测定水样中15种农药残留

利用低温冷冻条件下农药在水相和有机相之间达到新的传质平衡,建立了低温富集液液萃取-气相色谱-三重四极杆串联质谱法同时测定水样中15种有机磷、有机氯及菊酯类农药的方法。通过对样品前处理中的溶剂选择、冷冻温度及冷冻时间的优化,最终确定的样品前处理条件为:萃取溶剂为甲苯2.0 mL;冷冻温度-40℃;冷冻时间1h。15种农药的检出限(3S/N)在0.005~0.02μg·L-1范围,测定下限(10S/N)为0.02~0.07μg·L-1。方法用于水样中农药的分析,加标回收率在78.8%~124%之间,测定值的相对标准偏差(n=5)在0.9%~9.1%之间。     

低温富集-GC-MS结合保留指数分析赣南脐橙果肉成分

应用低温富集液液萃取-气相色谱-质谱法测定了赣南脐橙果肉的成分。通过NIST库检索结合保留指数对赣南脐橙成分进行了定性分析,共鉴定出60种组分,主要包括萜烯类、酯类、醇类、烷烃类。与常温液液萃取提取的组分相比较,低温富集提取出两种新成分,亚油酸和亚麻酸;与常温液液萃取的富集倍数相比较,在常温液液萃取和低温富集萃取两种方法均提取出的共有成分中,其低温富集倍数基于高于常温富集倍数,最高达11.2。     

分散液液微萃取-气相色谱法测定水样中甲拌磷农药

建立了基于分散液液微萃取(DLLME)的新型样品前处理方法,并采用气相色谱/氢火焰离子化检测器对水样中痕量的甲拌磷农药进行了测定。考察了影响分散液液微萃取的因素包括萃取溶剂、分散剂、样品体积、萃取温度和离心速度等。在最佳实验条件下,对甲拌磷的富集倍数达到300倍;检出限为0.001μL/L;方法的线性范围为0.01~10μL/L,R2为0.9986;相对标准偏差为6.65%;回收率为104%。将分散液液微萃取法与单滴液相微萃取和离子液体-液相微萃取方法进行了对比,结果表明,分散液液微萃取技术具有操作简单、快捷(前处理时间小于5 min)、富集效果好、回收率高等优点。同时预言,将离子液体与分散液液微萃取结合,将会产生更加满意的结果。     

基于冷冻熔炼的液-液萃取样品富集技术研究

本文通过对区域熔炼原理及液-液萃取技术的探讨,发展了一种简单高效的基于冷冻熔炼的液-液萃取样品富集新技术.通过理论分析,探讨了冷冻熔炼、常温液-液萃取以及冷冻熔炼液-液萃取中溶质浓度的分布特征,通过富集效率的探讨证明冷冻熔炼液-液萃取技术是液-液萃取与区域熔炼技术的结合.通过葡萄汁样品的分析,对该技术进行了评价.理论计算求得冷冻熔炼液-液萃取中相应组分的富集效率为4.5,而试验测得富集效率为4.8,两者结果一致,说明冷冻熔炼液-液萃取是一种简单高效的样品富集技术.     

分散液液微萃取/气相色谱-质谱法同时测定烟用添加剂中8种烷基苯类香味有害物

建立了超声溶剂提取和分散液液微萃取(DLLME)相结合的提取、净化前处理技术,采用气相色谱-质谱法分析了烟用添加剂中的黄樟素、侧柏酮、龙蒿脑、胡薄荷酮、甲基丁香酚、香豆素、6-甲基香豆素和7-甲氧基香豆素8种烷基苯类香味有害物。对分散液液微萃取溶剂及其体积、分散剂及其体积、萃取时间等条件进行了优化。在最佳实验条件下,8种有害物的线性范围为0.4～928μg/L(r2≥0.998 9),检出限为0.04～0.24μg/L,定量下限为0.13～0.80μg/L,富集倍数为140～208倍,方法的加标回收率为90%～100%,相对标准偏差为2.4%～6.7%。与行业推荐的测定方法相比,该方法具有灵敏度高、富集效果好、回收率高等优点。     

液-液-液三相液相微萃取-高效液相色谱法检测尿样中的安非他明和氯胺酮

建立了液-液-液三相液相微萃取与高效液相色谱联用技术测定尿样中的安非他明和氯胺酮的方法。考察了萃取溶剂、料液相pH值、搅拌速度、萃取时间和接受相HCl浓度等因素对富集因子的影响,得到了萃取溶剂为300 μL甲苯,料液相pH值为11,接受相为1.0 μL 0.1 mol/L HCl,搅拌速度为600 r/min,萃取时间为50 min的最佳实验条件。在该条件下,获得了较高的富集因子;方法的线性范围为安非他明0.01～10 μg/mL,氯胺酮0.01～5 μg/mL,相对标准偏差均小于2%,检测限均为5 ng/mL (S/N=3)。建立的三相液相微萃取方法能有效地去除复杂基体的干扰,有机溶剂消耗少,萃取效率高,是一种有效、灵敏的样品前处理方法,适合于尿样中安非他明和氯胺酮的测定。     

液-液-液微萃取/高效液相色谱法测定人血浆中的西地那非和伐地那非

建立了液-液-液微萃取与高效液相色谱联用同时测定血浆中西地那非和伐地那非的方法。考察了萃取溶剂、溶剂体积、接受相液滴大小、搅拌速度和萃取时间等因素对富集因子的影响,得到了萃取溶剂为300 μL 甲苯、接受相为2 μL 0.2 mol/L HCl、搅拌速度为600 r/min和萃取时间为40 min的最佳实验条件。在该条件下,获得了较高的富集因子。两种组分的线性范围均为5 μg/L~1.0 mg/L,加标回收率高于87%,其相对标准偏差小于5%。以信噪比为3计,西地那非的检测限为1 μg/L,伐地那非为0.5 μg/L。该方法能有效地去除复杂基体的干扰,有机溶剂消耗少,萃取效率高,是一种有效的、灵敏的样品前处理方法,适用于血浆中微量西地那非和伐地那非的测定。     

溶剂浮选技术的研究现状与展望

溶剂浮选是一种被气泡传质效应强化的液-液萃取技术,具有高分离效率、高富集系数、传质温和、低有机溶剂消耗、操作简单等优点,广泛应用于仪器分析的样品前处理、水体中有机污染物的分离富集、天然产物中活性物质分离等领域。本文比较全面地综述了溶剂浮选技术的通用模式、分离参数、应用现状和理论研究进展;在此基础上,重点介绍了近些年溶剂浮选领域出现的一些新分离模式和应用领域:新的分离模式主要是"双水相浮选"和"气浮络合萃取",新的应用领域主要是样品前处理技术的新应用以及对天然产物提取液中活性物质的分离富集。     

UAE/SPE-GS/MS法同时测定纺织废物中17种氯苯类污染物

本文建立了超声波辅助萃取/固相萃取法-气质联用法(UAE/SPE-GS/MS)同时测定纺织固废物中17种氯苯类污染物的分析方法。从超声萃取溶剂、超声萃取时间、超声萃取温度和固相萃取小柱等前处理条件进行优化,以保留时间定性,外标法定量。结果表明,纺织固废样品在超声50℃的水浴中经二氯甲烷溶剂超声萃取30min后,再通过弗罗里硅土(Florisil)固相萃取柱净化,测得17种氯苯类污染物的回收率为80%～107.6%,相对偏差RSD(n=10)小于5.5%。     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.