液液萃取-气相色谱-质谱法测定墨水中的16种多环芳烃

采用液液萃取-气相色谱-质谱法测定墨水中的16种多环芳烃。样品经二氯甲烷液液萃取后,使用固相萃取技术进行纯化。在气相色谱分离中用DB-5MS色谱柱为固定相,在质谱分析中采用选择离子监测模式。16种多环芳烃在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3S/N)在5.0~30μg·kg-1之间。以空白样品为基体进行加标回收试验,所得回收率在60.6%~116%之间,测定值的相对标准偏差(n=6)在1.5%~5.3%之间。     

气相色谱-质谱法测定三七提取物中16种多环芳烃

提出了气相色谱-质谱法测定三七提取物中16种多环芳烃。样品用环己烷萃取,经凝胶渗透色谱净化处理后,采用HP-5MS色谱柱分离,电子轰击离子源-选择离子检测模式检测,外标法定量。16种多环芳烃的质量浓度在0.01~1.0mg·L-1范围内与其峰面积呈线性关系,方法的测定下限(10S/N)在0.3~9.5μg·kg-1之间。在0.01,0.05,0.1mg·kg-1添加水平下,16种多环芳烃的加标回收率在70.1%~111%之间,相对标准偏差(n=6)在3.0%~9.4%之间。     

气相色谱质谱法测定聚氨酯塑胶跑道中多环芳烃

建立了气相色谱质谱法测定聚氨酯塑胶跑道中多环芳烃的分析方法。方法以甲苯为提取剂,经过超声提取和硅胶柱净化后,用气相色谱质谱测定16种多环芳烃含量。在0.5,1.0,5.0 mg/kg添加水平下平均回收率分别为73.8%~88.6%,84.0%~92.3%,88.2%~103.5%,相对标准偏差RSD分别为2.4%~9.2%,1.3%~8.2%,0.92%~7.3%。使用该方法测定实物样品发现6份塑胶跑道样品中均含有不同浓度的多环芳烃。     

QuEChERS/气相色谱质谱法同时测定膨化食品中多环芳烃类物质

建立了同时测定膨化食品中12种多环芳烃(PAHs)的Qu EChERS/气相色谱三重四极杆质谱(GC-MS/MS)的方法。称取2 g(精确至0.01 g)样品,加入10 mL正己烷提取15 min,采用500 mg乙二胺-N-丙基硅烷化硅胶(PAS)和500 mg C18粉末进行净化,净化后进行GC-MS/MS分析测定。实验结果表明,12种多环芳烃在气相色谱中的分离度良好,在1~1000 ng/mL的浓度范围内线性关系良好。加标回收率测定范围为49%~130%,RSD在1.0%~10%(n=7)之间。检出限在0.20~0.66μg/kg之间,定量限在0.66~2.20μg/kg之间。该方法数据可靠、操作简单快捷、灵敏度高,适合大批量样品中PAHs的测定。     

GC–MS法同时测定聚氨酯塑胶跑道中16种多环芳烃

建立气相色谱–质谱法同时测定聚氨酯塑胶跑道中16种多环芳烃如萘、苊、二氢苊、芴、菲、蒽、荧蒽、苯并[b]荧蒽、芘、苯并[a]蒽、屈、苯并[k]荧蒽、苯并[a]芘、茚并[1,2,3-cd]芘、1-甲基奈、2-甲基萘的检测方法。样品采用甲苯为提取剂,经超声提取和硅胶柱净化后,用气相色谱–质谱法测定16种多环芳烃残留量。16种多环芳烃的质量浓度在0.2~10.0 mg/kg范围内与色谱峰面积呈良好的线性,线性相关系数r20.998,检出限为5.0~60.0μg/kg。回收率为72.4%~101.6%,测定结果的相对标准偏差为0.9%~7.2%(n=6)。该方法准确度高、精密度好,适用于聚氨酯塑胶跑道中多环芳烃多残留检测。     

固相萃取-气相色谱-质谱法测定地下水中多环芳烃

提出了固相萃取-气相色谱-质谱法测定地下水中16种多环芳烃的方法。样品经ENVIC18固相萃取柱富集,依次用丙酮5 mL和二氯甲烷10 mL将16种多环芳烃从固相萃取柱上洗脱,用K-D浓缩器浓缩后,供气相色谱-质谱仪测定。纯水或自来水经固相萃取处理后,再用于配制标准溶液并绘制标准曲线。16种多环芳烃的检出限(3S/N)均小于2.0 ng.L-1。用该法分析地下水样品,所得结果的相对标准偏差(n=7)小于14.0%,加标回收率在84.3%~112.3%之间。     

气相色谱-质谱法检测益智药材中16种多环芳烃

建立了气相色谱-质谱联用技术同时测定益智药材中16种多环芳烃(PAHs)的分析方法。最佳萃取条件为：取样品2.0 g,加入同位素内标后用无水乙醇、水混合溶解,以10 mL正己烷提取;提取液先过Florisil柱固相萃取,经氢氧化钾-乙醇溶液皂化,多环芳烃分子印迹柱固相萃取后,以5 mL二氯甲烷-正己烷(1∶1,体积比)进行洗脱;采用DB-EUPAH毛细管色谱柱进行分离,内标标准曲线法定量测定。在此条件下,16种多环芳烃的线性范围为1.0~200.0 μg/L(r2 ≥ 0.992 5);检出限(S/N=3)为0.3~1.0 μg/kg;在不同浓度(1、3、10 μg/kg)基质加标条件下,苯并［c］芴(BcFL)的加标回收率为65.4%~72.8%,日内相对标准偏差(RSD,n=6)为6.0%~7.4%,日间RSD(n=6)为8.5%;其他15种多环芳烃的加标回收率为89.3%~116%,日内RSD(n=6)为0.10%~6.1%,日间RSD(n=6)为1.2%~7.5%。该方法的前处理净化效果好、灵敏度高、准确度高,适用于益智药材中16种多环芳烃的定量检测。     

加速溶剂萃取-气相色谱法测定土壤中16种多环芳烃

利用加速溶剂萃取-气相色谱法测定土壤中16种多环芳烃的分析。研究了萃取时间、温度、压力、样品的粒度对萃取效率的影响及不同淋洗液在硅胶柱净化过程中对方法回收率的影响。实验结果表明,加速溶剂萃取方法对16种多环芳烃的萃取溶剂量小,萃取时间短萃取回收率分别在74%~95%之间;对标准样品的检出限为0.00004~0.02 mg/kg;方法RSD为4%~15%。用此方法测定了株洲土壤中的多环芳烃含量。     

凝胶色谱净化-气相色谱-质谱法同时测定烧烤肉制品中19种多环芳烃

提出了凝胶色谱净化-气相色谱-质谱法同时测定烧烤肉中19种多环芳烃含量的方法。烧烤肉样品经正己烷-二氯甲烷(1+1)溶液超声提取30min后,上清液经凝胶色谱净化,所得净化液用HP-5MS色谱柱分离,全扫描模式和选择离子监测模式测定。19种多环芳烃的峰面积与质量浓度在5~200μg·L-1范围内呈线性关系,检出限(3S/N)在0.1~0.5μg·kg-1之间。在20,40,80μg·kg-1 3个浓度水平进行加标回收试验,19种多环芳烃的回收率在58.0%~122%之间,相对标准偏差(n=6)小于21.5%。     

超声波提取–气相色谱–质谱联用法测定城市污水处理厂脱水污泥中16种多环芳烃

采用超声波提取,气相色谱–质谱联用法检测,建立城市污水处理厂脱水污泥中16种多环芳烃的测定方法。以二氯甲烷–正己烷(体积比为1∶1)为提取剂,超声波提取20 min。在优化的仪器条件下,16种多环芳烃的质量浓度在0.05~100μg/m L范围内与色谱峰面积呈良好线性关系(r≥0.999 3),方法的检出限在0.12~0.38μg/kg之间,加标回收率为80%~120%,测定结果的相对标准偏差小于4.5%(n=6)。该方法样品前处理简单、重现性好、检出限低、准确度高,适用于城市污水处理厂脱水污泥中16种多环芳烃的测定。     

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.     

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.     

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.     

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.