气相色谱-质谱法测定水产品中15种邻苯二甲酸酯类塑化剂的残留量

建立了同时测定水产品中15种邻苯二甲酸酯类塑化剂残留的气相色谱-质谱(GC-MS)分析方法。样品经二氯甲烷-正己烷(1∶1)混合溶液超声萃取,中性氧化铝玻璃层析柱净化,用正己烷、二氯甲烷-正己烷(1∶9)混合液、乙酸乙酯-正己烷(1∶4)混合液和乙酸乙酯依次洗脱目标物,洗脱液经浓缩后正己烷定容,气相色谱-质谱测定。结果显示,15种邻苯二甲酸酯的线性范围为0.05～1.0 mg/L,相关系数(r)不小于0.999 1,检出限(LOD,S/N=3)为0.04～1.18μg/kg,定量下限(LOQ,S/N=10)为0.20～4.00μg/kg,不同水产品样品中添加2、50、200μg/kg的15种PAEs,平均加标回收率为81%～123%,相对标准偏差(RSDs,n=3)均小于15%。该方法稳定、可靠、操作简便,适用于鱼肉等水产品中多种PAEs的同时检测与确证。     

GC-MS法测定植物提取物中19种邻苯二甲酸酯类化合物

建立了植物提取物中19种邻苯二甲酸酯类化合物(PAEs)的气相色谱-质谱(GC-MS)分析方法。样品经水溶解,正己烷提取,弗罗里硅土小柱净化,采用GC-MS法在选择离子监测模式(SIM)下进行测定。结果表明:方法在0.1～10 mg/kg范围内具有良好的线性关系,相关系数均大于0.999,检测限为0.14～1.2μg/kg,加标回收率为62.1%～118.2%,相对标准偏差为0.61%～13%。方法可满足植物提取物中PAEs的定性和定量测定。     

应用磁性氧化石墨烯作为吸附分离净化剂-气相色谱-质谱法测定植物油中16种邻苯二甲酸酯类塑化剂含量

气相色谱-质谱法(GC-MS)测定植物油中16种邻苯二甲酸酯类塑化剂(PAEs)的第一步是提取样品中的PAEs。取样品0.500 0g,加入正己烷100μL和乙腈2mL,超声提取5min,离心5min,收集上清液,于留存的下层液相中再加乙腈2mL,重复提取1次。所得上清液与第一次上清液合并在40℃氮吹蒸发至近干。于残渣中加入乙腈1mL使溶解。在此溶液中依次加入无水硫酸镁250mg,N-丙基乙二胺(PSA)80mg和磁性氧化石墨烯50mg,超声萃取5min,通过外加磁场收集经净化的上清液,供GC-MS分析。在GC分析中,采用RXI-5si1MS色谱柱,按程序升温(在80～280℃区间)进行色谱分离,进样量为1μL。在MS分析中采用电子轰击离子源(EI)和选择离子监测(SIM)模式。用基质匹配法绘制标准曲线,测得16种PAEs的线性范围均在0.02～1.00mg·L~(-1)之间,其检出限(3S/N)为0.005～0.008mg·kg~(-1)。以空白植物油为基体,用标准加入法进行回收试验,测得回收率在82.2%～111%之间。16种PAEs测定值的相对标准偏差(n=6)在1.0%～7.2%之间。应用此方法分析了市购的5种植物油样品,并在样品中检出5种PAEs。     

基于四通道色谱分离仪净化-GC-MS法测定土壤中邻苯二甲酸酯类残留

建立了四通道色谱分离仪净化-气相色谱-质谱(GC-MS)法同时检测土壤中6种邻苯二甲酸酯(PAEs)类化合物的分析方法。样品经正己烷-丙酮(1:1,V:V)超声提取、四通道色谱分离仪净化(以正己烷-丙酮(1:1,V:V)洗脱)、GC-MS选择SIM模式测定。结果表明:6种PAEs类化合物在0.02~10 mg/L范围内定量离子的峰面积与质量浓度具有良好的线性关系(r0.9988),仪器检出限(LOD)为0.51~3.52μg/L,在3个浓度水平的加标回收率为83.7%~108.8%,相对标准偏差(RSD)为3.4%~11%。该方法可满足土壤中邻苯二甲酸酯类残留物的分析检测。     

液相色谱-串联质谱法测定水产品中甲氨基阿维菌素的残留量

提出了液相色谱-串联质谱法(LC-MS/MS)测定水产品中甲氨基阿维菌素残留量的方法。取水产样品5.00 g,用12.5 mL乙酸乙酯超声10 min,振荡15 min,重复提取一次，合并上清液并用乙酸乙酯定容至25 mL。取0.5 mL上述溶液，于45℃氮吹至干，残渣用80%(体积分数)乙腈溶液1 mL溶解，超声后用乙腈饱和正己烷溶液2 mL液液萃取净化。净化后的下层溶液过0.22μm疏水性聚四氟乙烯(PTFE)滤膜，在Atlantis T3色谱柱上分离，以不同体积比的乙腈和5 mmol·L^-1甲酸溶液混合液为流动相进行梯度洗脱，用LC-MS/MS检测，外标法定量。结果表明，甲氨基阿维菌素的质量浓度在0.01～2.0μg·L^-1内与对应的峰面积呈线性关系，测定下限(10S/N)为0.5μg·kg^-1。按照标准加入法进行回收试验，回收率为84.3%～99.9%,测定值的相对标准偏差(n=6)均小于7.0%。方法用于分析50个实际样品，仅1个进口鲑鱼检出甲氨基阿维菌素，检出量为20.7μg·kg^-1。     

气相色谱-质谱联用测定食品中的邻苯二甲酸酯

建立了食品中15种邻苯二甲酸酯类增塑剂的超声提取-固相萃取净化/GC-MS分析方法。考察了不同类食品的提取、净化方法,对检测的色谱条件进行优化,并通过基质加标校准曲线补偿邻苯二甲酸酯的基体效应。研究表明,净化后食品萃取液的基质去除率达到80%;15种邻苯二甲酸酯的方法线性范围为1～800μg/kg,相关系数大于0.998;加标样品的平均回收率为84%～115%,RSD(n=6)为5.3%～9.4%。含油脂食品的检出限为0.50～3.20μg/kg;不含油脂食品和液体食品的检出限为0.02～0.50μg/kg。该方法前处理过程简单、溶剂用量小、净化效果好,可用于不同种类食品中15种邻苯二甲酸酯类增塑剂的测定。     

HPLC-MS/MS同时测定水产品中喹烯酮、喹乙醇和5种大环内酯类抗生素残留

建立了水产品中喹烯酮、喹乙醇和5种大环内酯类抗生素同时测定的高效液相色谱串联质谱法。向样品中加入无水硫酸钠,以乙酸乙酯-乙腈的混合溶液为提取剂,用正己烷净化。以乙腈-10 mmol/L甲酸铵溶液为流动相,流速为0.3 mL/min,以Hypersil GOLD为色谱分离柱,用配有电喷雾离子源的三重四极杆质谱进行定性定量分析。在1～1000 ng/mL范围内,7种药物呈良好线性关系。在鲫鱼、南美白对虾和甲鱼空白肌肉中添加水平为2～10μg/kg时,该方法的回收率为67.52%～108.89%,相对标准偏差为4.2%～14%,方法检测限为1μg/kg,定量限为2μg/kg。方法适用于同时测定水产品中喹烯酮、喹乙醇和5种大环内酯类药物的残留量。     

气相色谱-串联质谱法测定大豆提取物中16种多环芳烃和16种邻苯二甲酸酯类

建立了大豆提取物中16种多环芳烃(PAHs)和16种邻苯二甲酸酯类(PAEs)残留的快速检测方法。样品用水溶解、正己烷超声提取,提取液经乙二胺-N-丙基硅烷粉末分散固相萃取净化后,采用气相色谱-三重四极杆串联质谱法在选择反应监测模式下进行测定。结果表明:32种化合物在0.01～5.0μg/mL范围内呈良好线性,相关系数不低于0.99,方法的检测限为0.1～10.0μg/kg。在30～100μg/kg加标水平下的回收率为62.1%～126.9%,RSD为3.2%～15%。方法适用于大豆提取物中PAHs和PAEs的测定。     

高效液相色谱测定肉制食品中五种邻苯二甲酸酯

建立了肉制食品中5种邻苯二甲酸酯类增塑剂(PAEs)含量的检测方法.样品用正己烷提取,C18柱分离,柱温35.0℃,乙腈.水为流动相梯度洗脱,流速1.0 mL/min,紫外检测波长226 nm.5种PAEs分离特异性好,在0.02～10μg/mL之间均具有较好的线性关系,检出限在4.4～13.8 ng/mL之间,高、中、低3水平的回收率均在79.5%～102.0%之间,相对标准偏差均在1.1%～14%之间.方法适用于肉制食品中邻苯二甲酸酯类的检测.     

固相萃取-气相色谱-质谱法测定食品中23种邻苯二甲酸酯

建立了同时检测食品中23种邻苯二甲酸酯类化合物的固相萃取-气相色谱-质谱(GC-MS)分析方法。样品经正己烷或乙腈提取、玻璃ProElut PSA固相萃取柱净化,GC-MS选择离子监测模式(SIM)测定。考察了不同种类食品的提取、净化方法。23种邻苯二甲酸酯的线性范围除邻苯二甲酸二异壬酯(DINP)和邻苯二甲酸二异癸酯(DIDP)为0.5～5 mg/L外,其余均为0.05～5 mg/L,相关系数(r)除DIDP外均大于0.99。方法的检出限(信噪比为3)为0.005～0.05 mg/kg,定量限(信噪比为10)为0.02～0.2 mg/kg。在10种食品基质中3个加标水平的平均回收率为77%～112%,相对标准偏差(RSD,n=6)为4.1%～12.5%。该方法稳定、可靠,操作简单,适用于食品中邻苯二甲酸酯类化合物的检测与确证。     

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.