超高效液相色谱-串联质谱同时检测血液中29种农药

本文采用超高效液相色谱-串联质谱法(UPLC-MS/MS)和固相萃取法(SPE)建立了血液中29种农药同时筛查、定性、定量分析的方法,血液经4%磷酸水溶液稀释后,震荡10min,以8000r·min-1转速离心10min,取上清液过3mL甲醇和3mL水活化好的Oasis Prime HLB(3cc,60mg)固相萃取小柱,使用3mL5%甲醇水淋洗,3mL乙腈甲醇混合溶剂(90:10)洗脱,接收洗脱液后在40℃条件下氮吹仪吹干,使用0.5mL初始流动相复溶,震荡10s后,过0.22μm水膜,装液质小瓶后进样分析。采用ACQUITY UPLC HSS C18色谱柱(150 mm×2.1mm,1.8μm)分离,流动相为0.1%甲酸乙腈-水/甲酸/甲酸铵(5mmol,pH=3),梯度洗脱,电喷雾电离正离子模式(ESI+),多反应选择离子监测模式(MRM)检测。29种农药的检出限为0.1 ng·mL^-1~5 ng·mL^-1,定量限为0.5 ng·mL^-1~10 ng·mL^-1,回收率为62.4%~97.4%,基质效应为82.8%~109%,相对标准偏差小于10.3%,相关系数均大于0.99,线性关系良好范围为10 ng·mL^-1~1000ng·mL^-1。本文方法灵敏度高,可以对血液中29种农药成分进行筛查、定性、定量分析,能够满足实际血液样品中农药成分检测的需求。     

顶空固相微萃取-气相色谱法测定辣椒根系分泌物中邻苯二甲酸酯类化合物

用顶空固相微萃取法提取样品中5种邻苯二甲酸酯类化合物(PAEs),用气相色谱法测定其含量。移取水栽培法培育辣椒的营养液10mL,置于顶空瓶中,进行固相微萃取到达要求的时间后,将萃取头迅速插入色谱仪进样口进行解吸。选用65μm PDMS/DVB纤维头作为微萃取头,并在下述条件下进行固相微萃取:①萃取时间及温度:50min,80℃;②样品体积:10mL;③搅拌速率:1 000r·min-1;④样品溶液的离子强度:氯化钠加入量达18%;⑤溶液的酸度:近中性,样品溶液的原始酸度(pH 6.5~7.2)正符合此要求;⑥解吸温度和时间:250℃,10min。结果表明:5种PAEs的线性范围均在0.2~10mg·L-1之间,检出限(3S/N)均小于0.12mg·L-1。方法的回收率在83.4%~105%之间,测定值的相对标准偏差(n=5)均小于9%。     

超高效液相色谱-三重四极杆质谱法测定地表水和废水中的19种磺胺类抗生素北大核心CSCD

样品采集于棕色高密度聚乙烯瓶或玻璃瓶中,尽快进行前处理,于4℃保存不超过7d。水样经0.45μm滤膜过滤,移取1L,加入1g的Na2EDTA,用0.1mol·L-1 NaOH溶液调节样品溶液的pH至6.0,采用OASIS HLB固相萃取柱对待测物进行富集萃取,用10 mL水洗涤小柱,真空干燥10min,再用10mL甲醇洗脱待测物,收集洗脱液,氮吹浓缩至干,用初始流动相定容至1mL,加入1.00 mg·L-1的内标混合溶液50μL,过0.20μm亲水性聚丙烯滤膜后,采用HYPERSIL GOLD C18色谱柱(100mm×2.1mm,1.9μm)分离待测物,以0.05%(体积分数)甲酸溶液和甲醇为流动相进行梯度洗脱,质谱分析中采用电喷雾正离子源和多反应监测模式。19种磺胺类抗生素的线性范围均为2.0~100μg·L^(-1),检出限(3.143s)在0.6~2.0ng·L-1之间。加标回收率为77.6%~134%,测定值的相对标准偏差为1.9%~11%。方法应用于测定地表水和养殖企业废水中的抗生素残留,地表水中仅检出两种目标物,质量浓度分别为2.60,2.10ng·L-1,养殖企业废水检出7种目标物,质量浓度在2.82~34.3ng·L-1之间。     

气相色谱-串联质谱法测定茶叶中24种农药残留量

采用气相色谱-串联质谱法测定茶叶中24种农药残留量。茶叶样品经乙腈超声振荡提取,Cleanert TPT固相萃取柱净化,乙腈-甲苯(3+1)溶液洗脱。在气相色谱分离中用RTX-5MS色谱柱为固定相,在质谱分析中采用多反应监测模式。采用内标法定量,24种农药的线性范围均为0.005~1.0mg·L-1,检出限(3S/N)在0.2~1.2μg·kg-1之间。在0.01,0.1,1.0mg·kg-1等3个浓度水平进行加标回收试验,回收率在67.5%~122%之间,测定值的相对标准偏差(n=6)在0.60%~9.9%之间。     

超高效液相色谱-三重四极杆质谱法测定地表水和废水中的19种磺胺类抗生素

样品采集于棕色高密度聚乙烯瓶或玻璃瓶中,尽快进行前处理,于4℃保存不超过7d。水样经0.45μm滤膜过滤,移取1L,加入1g的Na2EDTA,用0.1mol·L-1 NaOH溶液调节样品溶液的pH至6.0,采用OASIS HLB固相萃取柱对待测物进行富集萃取,用10 mL水洗涤小柱,真空干燥10min,再用10mL甲醇洗脱待测物,收集洗脱液,氮吹浓缩至干,用初始流动相定容至1mL,加入1.00 mg·L-1的内标混合溶液50μL,过0.20μm亲水性聚丙烯滤膜后,采用HYPERSIL GOLD C18色谱柱(100mm×2.1mm,1.9μm)分离待测物,以0.05%(体积分数)甲酸溶液和甲醇为流动相进行梯度洗脱,质谱分析中采用电喷雾正离子源和多反应监测模式。19种磺胺类抗生素的线性范围均为2.0~100μg·L~(-1),检出限(3.143s)在0.6~2.0ng·L-1之间。加标回收率为77.6%~134%,测定值的相对标准偏差为1.9%~11%。方法应用于测定地表水和养殖企业废水中的抗生素残留,地表水中仅检出两种目标物,质量浓度分别为2.60,2.10ng·L-1,养殖企业废水检出7种目标物,质量浓度在2.82~34.3ng·L-1之间。     

全自动固相萃取-气相色谱法测定水中多氯联苯总量

应用全自动固相萃取-气相色谱法测定水中多氯联苯6个Aroclor系列的总量。以特征"指纹峰"为定性依据,用外标法定量。优化的固相萃取条件为:1固相萃取柱为Bond Elut C18柱;2水样体积1.0L;3水样流量10mL·min-1;4洗脱剂为15mL二氯甲烷和15mL乙酸乙酯。用DB-5MS柱分离,电子捕获检测器检测。各多氯联苯的线性范围均为7.0~140.0μg·L-1,检出限均为0.7μg·L-1。以空白样品为基体进行加标回收试验,所得回收率在70.1%~90.0%之间,测定值的相对标准偏差(n=6)在4.3%~6.6%之间。     

气相色谱-质谱法测定胶基型嚼烟中烟碱的含量

取(1.42±0.01)g的试样5粒,溶解在5 mol·L-1氢氧化钠溶液8 mL和含内标的正己烷40 mL中,磁力搅拌110 min,静置20 min。取上层萃取液2 mL,用无水硫酸钠干燥,过0.22μm有机相滤膜。所得溶液采用DB-5MS色谱柱进行气相色谱分离。质谱分析采用选择离子监测模式。烟碱的线性范围为4.00~200 mg·L-1,检出限(3s)为0.19 mg·L-1。按标准加入法进行回收试验,回收率在91.0%~96.1%之间,测定值的相对标准偏差(n=6)均小于3.0%。     

气相色谱法同时测定大米中37种农药残留

提出了分散固相萃取-气相色谱法同时测定大米中37种农药残留量的方法。采用C18、乙二胺-N-丙基硅烷(PSA)和无水硫酸镁固相材料分散净化技术,以丙酮-正己烷(25+75)溶液为萃取溶剂,用脉冲火焰光度检测器和电子捕获检测器同时测定37种农药。13种有机氯农药的线性范围为0.02～0.2 mg.L-1,16种有机磷农药和8种拟除虫菊酯农药的线性范围为0.1～1.0 mg.L-1,方法的检出限(3S/N)均小于0.02 mg.kg-1。以大米样品为基体,加入三种不同浓度的农药标准溶液作回收试验,测定回收率在71.8%～111.8%之间,相对标准偏差(n=3)在1.1%～14.0%之间。     

自制四氧化三锰纳米粒子固相萃取-电感耦合等离子体质谱法测定蔬菜中铅和铜北大核心CSCD

采用自制四氧化三锰纳米粒子固相萃取-电感耦合等离子体质谱法测定蔬菜中铅和铜的含量。优化的固相萃取条件如下:(1)样品溶液的pH为4.0;(2)样品溶液的流量为1.0mL·min^(-1);(3)四氧化三锰纳米粒子的用量为50mg;(4)洗脱剂为3mol·L^(-1)盐酸溶液,用量为2mL;(5)样品溶液的体积为20mL。铅和铜的线性范围依次为0.01~5.0,0.02~1.0μg·L^(-1),检出限(3s/k)依次为4,8ng·L^(-1)。加标回收率为80.0%~108%,测定值的相对标准偏差(n=7)为0.94%~3.2%。     

自制四氧化三锰纳米粒子固相萃取-电感耦合等离子体质谱法测定蔬菜中铅和铜

采用自制四氧化三锰纳米粒子固相萃取-电感耦合等离子体质谱法测定蔬菜中铅和铜的含量。优化的固相萃取条件如下:(1)样品溶液的pH为4.0;(2)样品溶液的流量为1.0mL·min~(-1);(3)四氧化三锰纳米粒子的用量为50mg;(4)洗脱剂为3mol·L~(-1)盐酸溶液,用量为2mL;(5)样品溶液的体积为20mL。铅和铜的线性范围依次为0.01~5.0,0.02~1.0μg·L~(-1),检出限(3s/k)依次为4,8ng·L~(-1)。加标回收率为80.0%~108%,测定值的相对标准偏差(n=7)为0.94%~3.2%。     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.