高效液相色谱-串联质谱联用测定人血液中的全氟化合物

采用HPLC-ESI-MS/MS联用技术,建立了分析血样中9种全氟化合物(PFCs)的方法.以13C4标记的PFOS (MPFOS)作为内标物.以C18反相柱为分析柱,甲醇、醋酸铵为梯度洗脱淋洗液,9种分析物包括全氟己烷磺酸(PFHxS)、全氟庚酸(PFHpA)、全氟辛酸 (PFOA)、全氟辛烷磺酸(PFOS)、全氟壬酸(PFNA)、全氟癸酸(PFDA)、全氟十一酸(PFUnDA)、全氟十二酸(PFDoDA)和全氟十四酸(PFTA),在15 min内即可达到良好的分离.在血样前处理中,采用MTBE液-液萃取和固相萃取相结合的方法,进一步净化样品以延长色谱柱寿命;比较了4种固相萃取小柱对全氟化合物的萃取性能,最终选定HLB柱(Waters).本研究还讨论了两种C18反相柱Acclaim 120(50 mm×4.6 mm, 3 μm)和Acclaim120 (250 mm×4.6 mm, 5 μm)(Dionex) 对PFCs的分析性能,在本实验条件下,两种色谱柱具有相似的分离性能及检出限,线性范围在0.1～50 μg/L之间 (r≥0.9957);对于血液样品该方法的检出限在0.03～0.8 μg/L之间.本研究将该方法成功地应用于血样实际样品中全氟化合物的测定,加标回收除PFTA较低外,其它化合物均在74.2%～118.1%之间.     

混合无机酸消解-固相萃取-高效液相色谱-串联质谱法分析贝类壳体中的3种全氟磺酸化合物

建立了采用混合无机酸消解-固相萃取(SPE)-高效液相色谱-电喷雾电离串联质谱(HPLC-ESI-MS/MS)分析贝类壳体中的3种全氟磺酸化合物的方法。将贝壳粉经硝酸/盐酸混合酸消解,用氢氧化钠调节消解液的pH值至6后采用Oasis WAX固相萃取柱富集净化,然后采用内标法通过HPLC-ESI-MS/MS在分时段选择反应监测模式下分析上述全氟磺酸化合物。结果表明,该方法对于贝壳中全氟丁烷磺酸、全氟己烷磺酸和全氟辛烷磺酸的检出限(LOD)分别为0.28, 0.42和0.43 ng/g,加标回收率为94.88%～96.24%。采用此方法对渤海湾两种双壳贝类壳体进行的采样分析也表明,贝壳中3种目标污染物的含量范围为＜LOD～0.70 ng/g,比其在贝类软组织中的含量低约1个数量级。实验结果表明混合酸消解-SPE提取是检测贝类壳体中此类污染物的有效前处理方法。     

杂质延迟法去除液相系统中全氟辛酸的干扰

建立了高效液相色谱-串联质谱法(HPLC-MS/MS)对水体中7种全氟烷基酸(C4~C10)和全氟辛烷磺酸的分析方法。水样抽滤除去颗粒物杂质,加入回收率指示物,再使用WAX固相萃取柱富集和净化,提取液浓缩后,使用HPLC/MS/MS分析检测。仪器分析过程中,由于液相系统无法避免含氟材料的使用,引入了较高的全氟辛酸(PFOA)污染。本研究使用杂质延迟法实现了液相系统中PFOA和样品中PFOA的分离。在系统干扰去除后,水体中PFOA的方法检出限降低为0.8 ng/L(取样量500 mL),低定量浓度为3.2 ng/L;其它目标物的方法检出限为0.2~1.2 ng/L,低定量浓度为0.8~4.8 ng/L。本方法具有良好的重现性,6次平行样品测定中各检出化合物的相对标准偏差(RSD)均小于16%,6次基体加标实验中各目标物的回收率为87%~129%,RSD<15%。杂质延迟法有效的去除了系统干扰,降低了方法检出限,提高了方法精密度。     

高效液相色谱-串联质谱法测定医用口罩中8种全氟化合物

采用高效液相色谱-串联质谱(LC-MS/MS)技术建立了医用口罩中全氟辛酸、全氟辛烷磺酸钾、全氟十一酸、全氟十二酸、全氟辛烷磺酸胺、全氟十三酸、全氟十四酸、N-乙基全氟辛烷磺酸胺8种全氟化合物的测定方法。样品以甲醇为溶剂,超声提取,采用C₁₈(150 mm×2.1 mm, 5μm)色谱柱分离,流动相为甲醇和乙酸铵,梯度洗脱,多反应监测(MRM)模式进行分析检测,外标法定量。结果表明：8种全氟化合物的定量限(LOQ,以信噪比>10计)为0.50～1.58μg/kg,在0.5～10μg/L时标准曲线线性关系良好(r>0.9979),样品加标回收率为98.4%～102.3%,相对标准偏差为1.55%～7.44%。该方法前处理简单,回收率高,精密度好,适用于医用口罩中全氟化合物的检测。     

固相萃取-超高效液相色谱/串联质谱法同时测定水中27种磺酰脲类除草剂

采用固相萃取,用超高效液相色谱-串联质谱法(UPLC-MS/MS)建立了水中27种磺酰脲类除草剂的分析方法。通过对固相萃取柱、淋洗液、流动相等的优化,确定以Oasis HLB固相萃取柱、乙腈为淋洗液、0.1%乙酸-甲醇(7∶3,V/V)为流动相做水样预处理。在最优条件下,目标物回收率均为79.8%~124.5%,相对标准偏差(RSDs)为6.9%~9.6%,线性范围均为1~2 000μg/L,线性相关系数(R2)在0.999以上。该方法具有检测限低、回收率高等优点,经实际样品测试,可适用于水中27种磺酰脲类除草剂残留的同时检测。     

固相萃取-超高效液相色谱-三重四极杆质谱联用同时测定水中菊酯类农药多残留

应用固相萃取-超高效液相色谱-三重四极杆质谱(UPLC-MS/MS)联用技术,建立了水中20种菊酯类农药多残留的分析方法。通过对固相萃取柱、淋洗液、流动相等条件的优化,确定以Oasis HLB为固相萃取柱、正己烷-丙酮(9∶1,V/V)为淋洗液、0.1%乙酸水溶液-乙腈(7∶3,V/V)为流动相做水样预处理。在最优实验条件下,目标物的回收率为73.4%~124.5%,相对标准偏差(RSD)在5.7%~9.1%之间,线性范围均在1~2 000μg/L,各目标物标准品在UPLC-MS/MS系统中有效的线性相关(R2)为0.999以上。该方法具有检测限低、回收率高等优点,经实际样品测试,可适用于水中20种菊酯类农药多残留的同时检测。     

复合分子印迹固相萃取-HPLC-MS/MS法测定植物源性食品中多种农药残留

建立了复合分子印迹固相萃取(CMISPE)-高效液相色谱-三重四级杆串联质谱(HPLC-MS/MS)同时检测多种植物源性食品中20种三嗪类和磺酰脲类除草剂残留的分析方法。样品经乙腈提取后,利用液液萃取及复合分子印迹固相萃取小柱净化。液相色谱以乙腈和1%甲酸溶液作为流动相梯度洗脱,C8色谱柱分离,在多反应监测(MRM)正离子电喷雾扫描模式下进行HPLC-MS/MS分析。结果表明:20种除草剂在0.5~20 ng/m L范围内线性关系良好,相关系数均在0.99以上。对玉米样品进行3个水平的加标回收试验(5,10,20μg/kg),20种目标化合物的回收率在62.7%~117.4%之间,相对标准偏差(n=6)为1.7%~13.9%。检出限(S/N≥3)均小于0.63μg/kg,定量限(S/N≥10)均小于2.1μg/kg。方法适用于植物源性食品中20种三嗪类及磺酰脲类农药残留的检测。     

近岸及河口海水中全氟化合物的固相萃取富集/超高效液相色谱-串联质谱测定

建立了近岸及河口海水中全氟辛基磺酸(PFOS)、全氟辛酸(PFOA)、全氟十一酸(PFUn A)、全氟十二酸(PFDo A)、全氟十三酸(PFTr DA)、全氟十四酸(PFTA)6种全氟化合物(PFCs)的超高效液相色谱-串联质谱(UHPLC-MS/MS)测定方法。使用C18固相萃取小柱对500 m L水样中的目标物进行富集后,用15 m L甲醇-乙酸乙酯混合淋洗液(4∶1)进行洗脱,浓缩,定容至1.0 m L后,用Kinetex XB-C18色谱柱以均含5.0mmol/L甲酸铵的甲醇-水为流动相梯度洗脱方式进行分离,电喷雾负离子模式(ESI-)电离,多重反应监测模式(MRM)以及内标法对6种PFCs进行定性定量测定。优化了固相萃取、色谱分离及质谱测定条件,考察了海水盐度对方法回收率的影响。在优化实验条件下,方法在2.0,5.0,10.0 ng/L加标水平下,实际海水样品的回收率为80.1%~117.4%,在2.0 ng/L加标水平的相对标准偏差(RSD,n=7)为8.2%~12.1%。6种PFCs的线性范围为0.5~50.0μg/L,相关系数大于0.999 0;方法的定量下限(LOQ,S/N=10)为0.5~1.5 ng/L。该方法具有样品前处理简单、分析速度快、选择性好的特点,适用于近岸及河口海水中全氟化合物的快速测定。     

UPLC-MS/MS法检测肉类组织中的11种全氟化合物

建立了肉类组织中11种常见全氟化合物(全氟丁烷磺酸、全氟己烷磺酸、全氟庚酸、全氟辛酸、全氟辛烷磺酸、全氟壬酸、全氟癸酸、全氟十一酸、全氟癸烷磺酸、全氟十二酸、全氟十四酸)的Waters OasisHLB固相萃取净化/超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法。肉类组织中加入内标,经乙腈均质、提取后,用玻璃纤维真空抽滤,再用乙腈饱和的正己烷除脂净化,经Waters Oasis HLB固相萃取小柱富集净化,氮吹浓缩,超高效液相色谱(UPLC)分离,以2 mmol/L醋酸铵-2 mmol/L醋酸铵甲醇溶液为流动相,使用串联四极杆电喷雾离子源负离子扫描,多反应监测(MRM)模式检测,内标法定量。11种全氟化合物在0.50～20.0μg/L范围内线性关系良好,方法的检出限为0.014～0.060μg/kg,定量下限为0.047～0.199μg/kg,回收率为70.9%～107.1%,相对标准偏差(RSD,n=6)为0.4%～11.4%。该方法具有净化效果好、定量准确、灵敏度高的特点,适用于肉类组织中11种常见全氟化合物的快速确认和准确定量。     

液相色谱-串联质谱法测定小型家用电器塑料部件中全氟辛酸

建立了高效液相色谱-串联质谱(HPLC-MS/MS)结合加速溶剂萃取测定小型家用电器塑料部件中全氟辛酸(PFOA)的分析方法。样品冷冻粉碎后采用甲醇作溶剂进行快速溶剂萃取,萃取液经C18固相萃取柱富集净化后,以C18柱为分离柱,以甲醇-水为流动相,梯度洗脱,电喷雾负离子模式下多反应监测(MRM))模式检测。PFOA在0.5～100.0μg/L范围内线性关系良好(r2=0.998 9),回收率为93%～107%,相对标准偏差为2.9%～7.6%,检出限(S/N=3)为0.5μg/kg。该方法操作简便、灵敏度高,适用于小型家用电器塑料部件中全氟辛酸残留分析。     

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.     

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.     

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.     

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.     

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.