凝固-漂浮分散液液微萃取-高效液相色谱法测定水样中氯酚

采用凝固-漂浮分散液液微萃取(SFO-DLLME)-高效液相色谱法测定水样中3种氯酚.以密度小于水,且凝固点为24 ℃的1-十二醇为萃取剂,甲醇为分散剂,对水样进行分散液液微萃取.将混合液离心,再通过冷冻凝固操作使漂浮的萃取剂和水相分离,萃取剂复溶后进样测定.本实验确定的最佳实验条件为:萃取剂200 μL、分散剂300 μL、1.2 g NaCl、1 mol/L H3PO4 200 μL、样品体积8.0 mL、萃取时间3 min.3种氯酚测定的线性范围为0.05～6.0 mg/L;检出限为20～38 μg/L.应用本方法分析实际水样,加标回收率在90.11%～107.7%之间;日间相对标准偏差在3.5%～4.6%之间.本方法扩展了分散液液微萃取萃取剂的选择范围,具有简便、快速、准确、环境友好等特点.     

分散液液微萃取-柱前衍生-高效液相色谱法测定水样中双酚A

建立了分散液液微萃取-柱前衍生-高效液相色谱法测定水样中双酚A的分析方法.通过交互正交试验和混合型优化实验设计对影响因素(萃取剂体积、分散剂类型及其体积、水样体积、pH值及离子强度)进行了优化.优化后的分散液液微萃取条件为:60 μL萃取剂,0.4 mL分散剂(甲醇),pH 4.0;优化后的柱前衍生化条件:0.1 mL 2.0 g/L衍生剂(对硝基苯甲酰氯)、衍生化时间30 min;方法的线性范围:0.002～0.2 mg/L(r=0.9997),检出限0.007 μg/L(S/N=3);不同浓度双酚A的萃取率为59.0%～63.0%,相对标准偏差(RSD)2.5%～9.2%(n=5);水样中双酚A的加标率为86.5%～107.1%,RSD为4.0%～11.9%(n=5),其它雌激素(雌酮、雌二醇、雌三醇和17α-乙炔基雌二醇)对双酚A的测定无干扰.本方法可以对水环境中的痕量BPA进行检测,具有操作简便、快速等优点.     

超声辅助离子液体分散液相微萃取-高效液相色谱法测定废水中雌激素的研究

将离子液体、分散液相微萃取与超声萃取技术结合,采用疏水性离子液体1-丁基-3-甲基咪唑六氟磷酸盐([C4 MIM][PF6])为萃取剂,建立了超声辅助离子液体分散液相微萃取-高效液相色谱法分析废水中3种雌激素物质(己烯雌酚、双烯雌酚、己烷雌酚)方法.试验采用50μL的离子液体,考察了溶液体积、溶液pH值、超声时间、静置时间、离心时间等因素对富集效果的影响.最佳的萃取条件为:溶液体积为6 mL,甲醇体积0.3 mL,溶液pH值为2.0,超声时间6min,静置时间30min,离心时间10 min.在优化的萃取条件下,3种雌激素的富集倍数可达到96.8～112.4倍;方法的线性范围为0.5-100.0μg/L;检出限为0.25～0.50μ/L.对浓度为5.0μg/L的3种物质测定6次的相对标准偏差为9.2%～10.8%.     

超声辅助离子液体分散液液微萃取-反相液相色谱法测定水中丁醚脲残留

建立了超声辅助离子液体分散液液微萃取-反相液相色谱法分析水中丁醚脲残留的新方法。采用疏水性离子液体1-辛基-3-甲基咪唑六氟磷酸盐([OMIM]PF6)为萃取剂,乙腈为分散剂。考察了萃取剂和分散剂的种类及体积,超声、静置、离心时间,溶液pH值及盐度等因素对萃取效果和富集倍数的影响。使用Hypersil C18柱(200 mm×4.6mm i.d.,5μm ODS C18)液相色谱分离测定萃取液,流动相为100%甲醇、流速0.8mL/min、柱温25℃、检测波长为245nm。在优化实验条件下,丁醚脲的富集倍数、线性范围和检出限分别为358、0.01～1.0mg/L和0.8μg/L。运用此方法成功测定了实际水样(自来水、地下水、矿泉水)中的丁醚脲,样品的加标回收率和相对标准偏差(n=6)分别为81%～98%和1.2%～8.9%。     

固相萃取-分散液液微萃取-柱前衍生法测定水样中痕量雌激素

建立了碳纳米管的固相萃取-分散液液微萃取-柱前荧光衍生化(SPE-DLLME-PFD)测定水体中痕量雌三醇(E3)、双酚A(BPA)、17α-乙炔基雌二醇(EE2)及17β-雌二醇(E2)的高效液相色谱方法.采用中心复合设计和响应曲面法分析并优化SPE、DLLME及PLD条件,最佳条件为210 mL水样以2.0 mL/min的流速过固相萃取柱(碳纳米管量30 mg),甲醇洗脱,氮气浓缩并定容至0.6 mL(分散剂),将100 μL C6MIM[PF6]与分散剂的混合液注入到NaCl含量为25％的2.0 mL去离子水中,离心,移取20 μL下层有机相于样品瓶中,与4.0 mg衍生剂混合,在40℃水浴中衍生25 min;用0.1mL甲醇溶解过量的衍生剂颗粒,取20 μL进样分析.在优化条件下.4种雌激素的线性范围为0.05～5.00 μg/L,相关系数R2=0.9966～0.9999;,检出限介于0.13～6.33 ng/L(S/N=3)之间.不同加标浓度条件下,雌激素的加标回收率在83.1％～122.4％范围内(RSD=1.7％～9.6％).在实际水样中E3和BPA检出率较高.与其它方法相比,本方法虽然萃取时间长、水样量大、步骤多,但具有检出限低、操作简便、环境友好等优点.     

盐析辅助液液萃取/高效液相色谱-串联质谱法测定渔业水体中的7种喹诺酮类抗生素

利用盐析辅助液液萃取（SALLE）/高效液相色谱－串联质谱（HPLC－MS/MS）建立了测定渔业水体中环丙沙星等7种喹诺酮类抗生素的分析方法。水样用乙腈提取,硫酸镁盐析分层,提取液经氮吹浓缩后,采用Waters Atlantis C18 色谱柱 （150 mm × 2.1 mm,3.0 μm）以0.1%（体积分数）甲酸水溶液－甲醇为流动相进行梯度洗脱,采用电喷雾正离子模式检测,外标法定量。实验考察了水样pH值、萃取剂、盐析剂以及涡旋混合时间对萃取效率的影响。在最优的实验条件下,7种喹诺酮类抗生素在各自的质量浓度范围内线性良好,相关系数（r2）均大于0.995,检出限（LOD）和定量下限（LOQ）分别为3～10 ng/L和10～25 ng/L。对空白水样进行3个水平的加标回收实验,回收率为77.8%～104%,相对标准偏差（RSD）为3.1%～10%。该方法简单、灵敏、高效,可应用于渔业水体中喹诺酮类抗生素的检测。     

分散液-液微萃取/高效液相色谱法测定水样中的痕量双酚A

建立了分散液-液微萃取与高效液相色谱联用技术测定水样中痕量双酚A(BPA)的方法. 通过对实验条件的筛选及优化, 得到最佳条件: 22.5 μL氯苯作萃取剂、0.5 mL丙酮作分散剂、0 min静止萃取时间、调节pH 3.2左右、10%离子强度及9 mL水样体积. 此条件下方法的线性范围为0.5~100 μg/L(R2=0.9941), 检出限为0.10 μg/L. 在BPA质量浓度为1 μg/L条件下, 方法回收率为87.8%~111.0%, 相对标准偏差8.3%(n=5), 富集倍数范围1905~2527. 对添加不同BPA浓度的自来水、地表水及回用中水进行分析, 回收率分别为(108±11.1)%, (107±13.2)%及(81.2±6.2)%(n=3). 在既定的色谱条件下, BPA的测定不受乙炔基雌二醇、雌二醇、雌三醇、雌酮和壬基酚等雌激素的干扰.     

离子液体液-液萃取-高效液相色谱测定水中酚类化合物

建立了离子液体1-丁基-3-甲基咪唑六氟磷酸盐([C4mim][PF6])液-液萃取-高效液相色谱测定水中酚类化合物的方法.研究了水相pH值、萃取时间、水相体积及盐的浓度对萃取的影响.最佳萃取条件分别为:水相pH值为5,萃取时间为40 min,水相体积为60 mL.对比了离子液体对1-辛醇对苯酚、4-硝基苯酚、2-硝基苯酚、2,4-二甲基苯酚和双酚A的富集效率.在最佳条件下,离子液体对5种酚的富集倍率在9～151之间,方法对苯酚、4-硝基苯酚、2-硝基苯酚、2,4-二甲基苯酚和双酚A的检出限分别为:2.0、0.9、0.3、1.8和1.1 μg/L.将该方法应用于自来水、河水、湖水和污水的检测,回收率为87.9%～109.9%.     

超声辅助乳化液液微萃取-气相色谱-质谱分析水中的人工合成麝香

将超声辅助乳化与液液微萃取技术结合,建立了水体中人工合成麝香的气相色谱-质谱分析方法.优化前处理条件,包括萃取剂、萃取剂体积、萃取时间、萃取温度及离子强度的选择.结果表明:在10 mL水样中,加入50 μL氯苯作为萃取剂,4 0 MHz超声10 min,混匀,以4000 r/min离心10 min,移取下层有机相进样分析,效果佳.样品的富集倍数可达200倍,8种人工合成麝香在0.005～0.4 μg/L范围内线性关系良好,相关系数均大于0.994;检出限为0.3～0.5 ng/L;水样中加标回收率为96.2％～102.9％;相对标准偏差为2.3％～4.1％.本方法灵敏、快速、准确,可满足环境水样中痕量人工合成麝香监测的质控要求.     

环境水样中百菌清残留的单滴微萃取-反相液相色谱测定

应用单滴微萃取(SDME)-反相液相色谱(RPLC)检测了环境水样中的百菌清残留.优化了单滴微萃取条件:环己烷萃取剂6 μL、单滴体积2 μL、搅拌速率350 r/min、萃取时间40 min、水溶液温度35 ℃、无盐度.水样经单滴微萃取后,使用Hypersil C18柱反相液相色谱分离测定百菌清.反相液相色谱条件:100%甲醇流动相、流速1.0 mL/min、柱温25 ℃、224 nm检测.方法的线性范围、检出限、相对标准偏差和富集倍数分别为1.0 ～50 μg/L、0.02 μg/L、6.1%和427倍.采用该法对环境水样中的百菌清残留进行了测定,环境水样的加标回收率为98% ～106%.     

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.     

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.     

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.