高效液相色谱-电感耦合等离子体质谱联用同时检测海产品中的多种有机锡

利用高效液相色谱-电感耦合等离子体质谱(HPLC-ICP/MS)联用技术对5种有机锡[三甲基氯化锡(TMT)、二丁基氯化锡(DBT)、三丁基氯化锡(TBT)、二苯基氯化锡(DPhT)和三苯基氯化锡(TPhT)]进行了分离,采用Agilent TC-C18柱进行有机锡的形态分析,流动相为V(乙腈)∶V(H2O)∶V(乙酸)=65∶23∶12,0.05%的三乙胺,pH=3.0,流速为0.4mL/min,测定了0.5~100μg/L范围内5种有机锡化合物的混合标准工作曲线,其相关系数优于0.998(R2),方法的检出限均小于0.5μg/L。采用流动相对菲律宾蛤(Ruditapes Philippi-narum,R.P.)及毛蛤(Ark Shell,A.S.)样品进行超声萃取及高速离心后,用上述方法进行了分析。结果表明,海产品含有4种有机锡,其中TBT和TPhT的含量最高,为14.38~104.7μg/L(干重)。TMT、TBT和TPhT的加标回收率均优于80%。DPhT和DBT可能存在吸附或降解问题,因而回收率仅为37.3%~75.2%。     

高效液相色谱-电感耦合等离子体质谱联用测定沉积物中的多种有机锡

为了快速有效的检测沉积物中的多种有机锡,利用高效液相色谱-电感耦合等离子体质谱(HPLC-ICP/MS)联用技术对沉积物中的5种有机锡(三甲基氯化锡(TMT)、二丁基氯化锡(DBT)、三丁基氯化锡(TBT)、二苯基氯化锡(DPhT)和三苯基氯化锡(TPhT))的形态进行了分离,采用Agilent TC-C<,18>柱进...     

高效液相色谱-电感耦合等离子体质谱技术测定海水中锡化学形态

建立了反相色谱-电感耦合等离子体质谱联用技术(HPLC-ICP-MS),用于测定海水中一丁基锡(MBT)、二丁基锡(DBT)、三丁基锡(TBT)和三苯基锡(TPhT)。分别使用两种不同色谱柱C18ACE和TC-C18,缓冲溶液V(acetonitrile)∶V(water)∶V(acetic acid)∶V(TEA)=65∶23∶12∶0.005%,在分别在流速0.2和0.4 mL/min下对4种不同形态的锡进行分离。所建立的方法在20μL进样量下,对DBT、MBT、TBT及TPhT的检出限分别为30、50、80及10 ng/L。对青岛沿岸海水分析的结果表明海水中DBT、TPT含量分别为35和20 ng/L,而MBT及TBT的含量则低于本方法的检出限。     

高效液相色谱-电感耦合等离子质谱法分析水产品中有机锡的形态

建立了水产品中三甲基锡(TMT)、一丁基锡(MBT)、二丁基锡(DBT)、三丁基锡(TBT)、一苯基锡(MPhT)、二苯基锡(DPhT)、三苯基锡(TPhT)7种有机锡化合物的高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)的分离检测方法.方法利用Eclipse Plus C18反相色谱柱对水产品中7种有机锡化合物进行分离,利用电感耦合等离子体质谱对锡元素进行检测,外标法定量测定水产品中7种有机锡化合物的含量.研究采用30 mL 30％乙酸-甲醇提取液(V/V),低温超声萃取10 min后离心3 min,取上清液20 mL浓缩,用流动相定容至2 mL,以乙酸(0.2％三乙胺,V/V)-甲醇溶液为流动相,梯度洗脱,7种有机锡化合物在30 min内得到了有效分离.7种有机锡化合物标准曲线的线性相关系数大于0.995,检出限0.11 ～0.60 μg/kg.此前处理方法样品加标回收率为72.1％～ 111.7％.本方法操作简便,分离效果好,检出限低,适用于水产品中有机锡的检测.     

气相色谱-质谱法测定木材及木制品中的有机锡化合物

建立了木材及木制品中4种有机锡化合物的气相色谱-质谱)测定方法。选取松木和胶合板作为代表性样品,在空白样品中加入模拟防腐剂溶液,制成阳性样品用于实验条件优化。以乙醇为溶剂,超声提取样品中的有机锡化合物,加入乙酸-乙酸钠缓冲溶液(pH 5)调节溶液酸度,经2%四乙基硼化钠(NaBEt4)衍生、正己烷萃取后,GC-MS同时测定一丁基锡(MBT)、二丁基锡(DBT)、三丁基锡(TBT)和三苯基锡(TPhT)。在0.1～20 mg/L范围内,线线性良好,4种有机锡化合物的平均回收率为83.6%～103.2%;RSD小于9.8%。     

液相色谱-串联质谱法测定紫菜中三种三取代有机锡化合物

建立了液相色谱-串联质谱(LC-MS/MS)同时测定紫菜中三甲基锡(TMT)、三苯基锡(TPhT)和三丁基锡(TBT)的分析新方法。样品用二氯甲烷-乙酸乙酯(1∶1,V/V)混合溶剂进行超声提取,提取液经氮吹至近干,并用甲醇和水混合溶液(7∶3,V/V)定容,经活性炭净化。采用ZORBAX Eclipse plus C18色谱柱分离,流动相为甲醇-0.1%甲酸溶液(55∶45,V/V),流速为0.3mL/min。在正离子模式下采用多重反应模式(MRM)进行监测。有机锡化合物在1~100ng/mL浓度范围内线性良好,相关系数在0.9902~0.9918之间,TMT、TPhT和TBT的检测限分别为0.2ng/mL、0.4ng/mL和0.2ng/mL。在25、75ng/mL两个添加水平下回收率在72.3%~98.0%之间,其相对标准偏差均小于8.1%。该方法可用于紫菜中三种三取代有机锡化合物的同时测定。     

盐酸甲醇溶液提取-气相色谱-质谱法测定水生动植物样品丁基锡

采用四乙基硼酸钠(NaBEt4)为衍生剂,建立简单、高效的生物样品有机锡气相质谱(GC-MS)分析方法。结果表明,冷冻干燥生物样品粉末0.1 g经15 mL 0.035 mol/L盐酸甲醇振荡提取1 h,定量提取液加入乙酸盐缓冲溶液(pH 4.8)调节溶液酸度,用含内标物正己烷2 mL和0.5 mL 2%(m/V)NaBEt4水溶液衍生萃取30 min后,GC-MS同时测定一丁基锡(MBT)、二丁基锡(DBT)、三丁基锡(TBT)。在0.5~50μg/L范围内,线性良好,3种有机锡加标回收率均在80%以上。此方法能快速简单对复杂生物样品中的有机锡进行分析,其检出限约为0.01μg/L,3个平行样测量值标准偏差都在10%以内。     

气相色谱-质谱法测定纺织助剂中的有机锡

建立了纺织助剂中二丁基锡(dibutyltin, DBT)、三丁基锡(tributyltin, TBT)及三苯基锡(triphenyltin, TPhT)化合物的气相色谱-质谱联用(gas chromatography-mass spectrometry, GC-MS)检测方法。在乙酸-乙酸钠缓冲溶液(pH 4.0)中,用正己烷超声萃取(对疏水性样品)或振荡萃取(对亲水性样品)试样中的有机锡,然后以四乙基硼化钠的四氢呋喃溶液为衍生化试剂进行衍生化,用GC-MS测定,依据保留时间和选择离子定性,外标法定量。实验结果表明,在0.1～8.0 mg/L(对于DBT和TBT)或0.1～4.0 mg/L(对于TPhT)的范围内,有机锡化合物的浓度（以有机锡阳离子计）与其衍生物峰面积呈良好的线性关系,线性相关系数(r2)为0.9994～0.9998,检出限为0.003～0.005 mg/L; 4种聚氨酯类助剂基质中3种有机锡化合物的平均加标回收率为92.6%～108.0%,相对标准偏差为2.5%～10.2%。该方法的技术指标满足纺织助剂中有机锡化合物的测定要求。     

超声波提取-分散固相萃取净化-气相色谱法测定紫菜中三丁基锡和三苯基锡

建立了紫菜中三丁基锡(TBT)和三苯基锡(TPhT)化合物同时分析的气相色谱法.样品以乙酸乙酯-正己烷(体积比为4∶1)超声提取,四乙基硼酸钠衍生,衍生物经活性炭固相材料分散净化后,用响应面分析法对提取条件进行优化,最后采用气相色谱-火焰光度法(GC-FPD)测定.研究结果表明,TBT、TPhT这两种有机锡化合物在0.1～10 mg/L浓度范围内均线性良好,其相关系数分别为0.9989和0.9996;检测限分别为0.038和0.049 mg/L.在三个不同添加水平下,TBT、TPhT的平均回收率范围为80.3％～106.9％,相对标准偏差为5.1％～8.7％.该方法快速、准确,可应用于紫菜中TBT、TPhT的同时检测.     

高效液相色谱–氢化物发生原子吸收光谱法测定塑料食品包装材料中的有机锡

建立了高效液相色谱–氢化物发生原子吸收光谱法同时测定塑料食品包装材料中二甲基锡(DMT)、三甲基锡(TMT)、二丁基锡(DBT)和二苯基锡(DPh T)含量的方法。选择甲醇为溶剂,微波辅助萃取样品中的有机锡化合物,采用Eclipse Plus C18反相柱,在流动相为甲醇–水–乙酸(体积比为65∶33∶2)的混合溶液中,加入0.05%的三乙胺溶液作为离子对试剂,流速为0.6 m L/min时,4种有机锡化合物可达到有效分离。在4%盐酸溶液和2.5%硼氢化钠溶液的氢化反应条件下,4种有机锡化合物质量浓度在5~100μg/L范围内与对应吸收峰面积呈良好线性关系,其相关系数(r)均大于0.999。方法的检出限在0.35~0.50μg/L之间。样品平均加标回收率为86.4%~94.2%,测定结果的相对标准偏差小于7.4%(n=7)。该方法操作简单快速,分离效果好,适用于塑料食品包装材料中有机锡的快速检测。     

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.