超声辅助萃取气相色谱-质谱法测定松针中的多溴联苯醚

建立了测定松针样品中多溴联苯醚(PBDEs)的分析方法。松针样品经过正己烷-丙酮(体积比为1∶1)混合溶液超声萃取、浓硫酸和氧化铝柱净化后,采用气相色谱-负化学电离源质谱(GC-NCI-MS)选择离子监测(SIM)模式检测,内标法定量。结果表明,方法的加标回收率为83.8%~107.5%,三溴~七溴代联苯醚的仪器检出限为0.152~ 0.770 pg,十溴代联苯醚(BDE-209)的检出限为11.1 pg;三溴~七溴代联苯醚的方法检出限(湿重)为3~15 pg/g,BDE-209的方法检出限(湿重)为222 pg/g。方法具有良好的重现性、较高的灵敏度和良好的回收率。实际样品分析表明,松针中BDE-209是主要的同类物,约占8种PBDEs总量的82.3%,低溴代联苯醚以2,2′,4,4′-四溴联苯醚(BDE-47)为主。     

气相色谱-负离子化学源/质谱法(GC-NCI/MS)分析鱼类和贝类样品中多溴联苯醚和多溴联苯

将气相色谱-负离子化学源/质谱法(GC-NCI/MS)应用于分析鱼类和贝类样品中5种多溴联苯醚(PBDEs)和5种多溴联苯(PBBs)残留.鱼类和贝类样品以正己烷/丙酮(1∶1,V/V)作为提取剂,采用超声萃取法,提取液经酸性硅胶和中性硅胶层析柱净化和正己烷洗脱后,以PCB-103为内标物和GC-NCI-MS的选择离子...     

超声萃取-气相色谱-质谱联用测定海洋沉积物中39种多溴联苯醚残留

建立了超声萃取-气相色谱-质谱法测定海洋沉积物中39种多溴联苯醚残留的分析方法.样品用V(正己烷):V(二氯甲烷) =1:1混合溶液提取,超声(控制水浴温度为25 ℃)提取60 min,采用硅胶和氧化铝净化,负化学离子源-气相色谱-质谱法进行检测,39种组分图谱在49 min 内能得到很好的分离. 39种混合样品的检出限为0.003～0.10 μg/kg; 加标回收率为66.2%～118.6%;相对标准偏差为0.8%～18.2%.用于实际样品分析,结果令人满意.     

土壤中10种多溴联苯醚的加速溶剂-固相萃取净化方法优化研究

建立了土壤中10种多溴联苯醚(PBDEs)的加速溶剂萃取-固相萃取净化-气相色谱分析测定方法.采用加速溶剂萃取(ASE)技术对土壤中10种PBDEs进行提取,并对4种萃取体系(正己烷、正己烷-丙酮(4∶1,V/V)、正己烷-丙酮(1∶1,V/V)、正己烷-二氯甲烷(1∶1,V/V))进行优化;采用固相萃取(SPE)技术对样品进行净化,制备了10种不同填料的SPE柱,通过洗脱实验和加标回收率实验对各SPE柱的净化性能进行对比筛选.最终优化条件为正己烷-丙酮(4∶1,V/V)体系提取,酸性硅胶柱净化.在优化条件下,10种PBDEs的回收率为74.4％ ～ 125.2％,相对标准偏差为4.4％ ～ 14.4％,方法检出限为0.04～0.22 ng/mL.本方法简单、快速、净化效果较好、重现性和回收率良好,可用于土壤样品中PBDEs的分析.     

同位素稀释-高分辨气相色谱/高分辨质谱法测定大气中多溴联苯醚和多溴联苯153

针对环境监测的特点和要求,建立了同位素稀释-高分辨气相色谱/高分辨质谱测定大气中多溴联苯醚(PBDEs)和多溴联苯153(BB153)的方法。采用正己烷/二氯甲烷(1:1, v/v)及正己烷分别对PBDEs和BB153进行快速溶剂萃取,并通过复合硅胶柱净化。在校准曲线最高浓度的10%和90%加标水平下得到的天然内标的平均回收率分别为100%和104%,平均相对标准偏差(n=7)分别为5%和6%;二至十溴代联苯醚和BB153相应的¹³C同位素标准物质回收率在36.5%~133%之间;而一溴代联苯醚¹³C同位素标准物质回收率较差,可能是由于物化性质与其他化合物不同。在实际采样体积为300 m³的情况下,未发生污染物穿透现象;分析物检出限低于2×10^-4 ng/Nm³,提取内标回收率在56%~126%之间(一溴代联苯醚除外)。实验结果表明该方法能对化合物准确定量,适用于大气中二至十溴代联苯醚和BB153的分析。     

凝胶渗透色谱-固相萃取结合色谱-质谱法测定乳制品中18种溴系阻燃剂

采用索氏提取、凝胶渗透色谱和固相萃取技术作为前处理方法,建立乳制品中6种新型溴系阻燃剂、8种多溴联苯醚、四溴双酚A和α、β、γ-六溴环十二烷异构体共18种溴系阻燃剂的同时提取与净化方法,并结合气相色谱-负化学源质谱法(GC-NCI/MS)和高效液相色谱-电喷雾电离-串联质谱法(HPLC-ESI-MS/MS)进行检测。奶样经冷冻干燥后以正己烷-丙酮(1：1, V/V)索氏提取,采用凝胶渗透色谱结合酸化硅胶柱净化,随后以LC-Si固相萃取柱分离气相和液相待测物。以GC-NCI/MS测定6种新型溴系阻燃剂和8种多溴联苯醚,以HPLC-MS/MS检测四溴双酚A和六溴环十二烷异构体,内标法定量。结果表明,以空白牛奶样品为加标基质,多数待测物平均回收率为80.1%~114.7%,方法具有良好的精密度(多数待测物相对标准偏差( RSD)在0.87%~14.9%)和灵敏度(检出限在0.2~119.2 pg/g之间),可满足乳制品中多种溴系阻燃剂同时提取、净化和检测需求。     

凝胶渗透色谱-分散固相萃取法同时测定鸡蛋中多溴联苯醚及其衍生物、四溴双酚A和六溴环十二烷

建立了一种同时检测鸡蛋中四溴双酚A(TBBP A)、六溴环十二烷(HBCD)和多溴联苯醚(PBDEs)及其衍生物羟基多溴联苯醚(OH-PBDEs)和甲氧基多溴联苯醚(MeO-PBDEs)的凝胶渗透色谱(GPC)-分散固相萃取(DSPE)-液相色谱-串联质谱(HPLC-MS/MS)和气相色谱-负化学源质谱(GC-NCI/MS)的检测方法。样品经正己烷、二氯甲烷(1∶1,V/V)加速溶剂萃取,凝胶渗透色谱净化后,经100 mg十八烷基键合硅胶(C18)分散固相萃取吸附剂去除杂质,液相色谱-串联质谱和气相色谱-负化学源质谱方法测定,外标法定量。在蛋白和蛋黄样品中添加1.0或5.0μg/kg的目标物,其回收率分别为64.5%~97.2%和65.6%~109.2%(除BDE-85为54.8%,OH-BDE-137为47.4%外),相对标准偏差小于20.2%,定量限为0.01~0.2μg/kg。     

固相萃取结合超高效液相色谱-串联质谱法及气相色谱-负化学源质谱法测定人血清中的四溴双酚A、六溴环十二烷和多溴联苯醚

建立了固相萃取同时提取、净化血清中四溴双酚A(TBBPA)、α, β, γ-六溴环十二烷(HBCD)和8种多溴联苯醚(PBDEs)同系物的样本前处理方法,并结合色谱-质谱分离分析技术检测人血清样本中该类化合物的含量。试样在加入各自的同位素内标物后以甲基叔丁基醚/正己烷(1:1, v/v)混合溶剂进行萃取,再经浓硫酸去除脂肪后,以LC-Si固相萃取柱分离HBCD/TBBPA和PBDEs。采用分步检测的方式,在50 mm长BEH C18反相色谱柱上以超高效液相色谱-串联质谱(UPLC-MS/MS)的多反应监测模式(MRM)检测HBCD和TBBPA,在15 m长的毛细管柱上以气相色谱-负化学源质谱(GC-NCI/MS)的选择离子监测模式(SIM)检测PBDEs。以胎牛血清为空白基质,当HBCD、TBBPA和BDE-209的加标水平为0.5 ng/g和5 ng/g、三溴至七溴联苯醚的加标水平为0.05 ng/g和0.5 ng/g时,它们的平均加标回收率为80.3%～108.8%,相对标准偏差为1.02%～11.42%(n=5);以信噪比(S/N)为3计算,方法的检出限(LOD)为1.81～42.16 pg/g。采用该方法对实际样品进行测定,结果表明,本方法快速、准确、灵敏度高,能够满足血清中HBCD、TBBPA和PBDEs残留的同时提取及测定的要求。     

气相色谱-负离子化学源-质谱法分析茶叶中5种多溴联苯醚

将气相色谱-负离子化学源-质谱法(GC-NCI-MS)应用于快速分析茶叶中5种多溴联苯醚残留量.茶叶样品以正己烷作为提取剂,采用超声辅助提取法,提取液经中性氧化铝和Florisil硅藻土层析柱净化和正己烷洗脱后,以PCB-103为内标物和GC-NCI-MS的选择离子监测方式(SIM)进行定性与定量分析.5种多溴联苯醚的平均加标回收率为70.9%～81.7%,相对标准偏差为6.9%～11.0%,方法检出限小于0.12 μg/kg,线性范围为0.1～500 μg/kg,相关系数都大于0.9990.所分析的8种茶叶样品中6种含有微量的PBDE-47,1种茶叶样品含有微量的PBDE-99.     

人体血清中的多溴联苯醚、邻苯二甲酸酯和双酚A的连续在线分离及气相色谱-质谱测定

建立了人体血清中多种环境雌激素:多溴联苯醚、邻苯二甲酸酯和双酚A的快速可靠的连续在线分离及在气相色谱-质谱上的分析方法.血清样品经过浓盐酸使蛋白质变性,用乙醚萃取,经硅胶柱分离出多个族组分:多溴联苯醚(Polybrominated diphenyl ethers,PBDEs)、邻苯二甲酸酯(Phthalate estcrs,PAEs)和双酚A(Bisphenol A,BPA),最后由气相色谱-质谱的选择离子检测测定.PBDEs,PAEs和BPA标准曲线回归方程拟合度R2均大于0.99,表明在测试的浓度范围内线性关系良好.PBDEs目标化合物的检出限为0.005～0.048μg/L,PAEs目标化合物的检出限为0.103～0.833μg/L,BPA的检出限是0.035 μg/L.标准样品重复样中,PBDEs的RSD(relative standard deviation)值分别为2.8％～10.9％;PAEs的RSD值为5.6％～9.9％;BPA的RSD值为3.0％.实际血清样品中,PBDEs的加标回收物PCB209(Polychloride diphenyl ether 209)的回收率范围是74.8％～88.5％;PAEs中的加标回收物DBP-D4(Dibutyl phthalateDeutorium 4)的回收率范围为78.7％～97.0％;BPA中的加标回收物BPA-D16( Bisphenol A-Deutorium 16)的回收率范围是76.3％～93.1％.本方法检测血液中多种环境雌激素灵敏度高、重现性和回收率均良好.     

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.     

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.     

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.     

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.     

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.     

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.