蛋白受体结合筛选-气质联用法测定动物组织中的氯霉素残留

建立了动物组织中氯霉素残留的蛋白受体结合筛选和GC MS分析方法。受体结合生物筛选的筛选限为0.1μg kg,假阴性率为零,其它常用抗生素的交叉反应率均<0.1%。筛选阳性样本经液液分配萃取、C18SPE固相萃取净化后衍生进行GC MS的NCI选择离子监测分析。其定量检出限为0 1μg kg,样品添加水平0 1～10μg kg时,回收率为76 2%～103 5%,相对标准偏差为7 5%～10 6%。     

气相色谱-负化学电离质谱测定蔬菜中啶虫丙醚的残留量

建立以固相萃取净化和气相色谱-负化学质谱(GC/NCI/MS)技术快速测定蔬菜中啶虫丙醚残留量的方法。经乙腈提取,共提物中的基体杂质经PSA/SAX固相萃取柱去除,用负化学源质谱检测,灵敏度选择性高于气相色谱-电子轰击源质谱。目标农药的平均回收率为87.0%～91.0%,平均相对标准偏差为6.45%～6.80%(n=7),方法的检出限为1μg/kg。     

基质固相分散和GC-NCI-MS法分析果汁中拟除虫菊酯农药残留量

建立了基质固相分散法（MSPD）和气相色谱-负化学离子源-质谱法（GC—NCI—MS）应用于果汁中10种拟除虫菊酯农药残留量的快速分析方法，并对这些农药NCI—MS的阴离子结构与断裂机理进行初步探讨。采用以中性氧化铝为吸附刺、Florisil硅藻土为净化剂和乙酸乙酯为洗脱剂的MSPD样品前处理方法，以PCB103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。当样品的加标浓度水平为50、250μg／kg时，平均加标回收率为86．7％～114．8％，相对标准偏差为1.9％～14．1％；除氯菊酯农药的方法检出限（MDL）为14.7μg／kg外，其余农药的MDL大都小于1．0μg／kg；线性范围为10～500μg／kg，相关系数都大于0.997，在所分析的大部分果汁中至少分析出两种以上的拟除虫菊酯农药残留。     

气相色谱-负化学离子源质谱法同时检测蔬菜中103种农药残留

本文比较了负化学电离(NCI)和电子轰击电离(EI)两种电离方式下采用气相色谱-质谱(GC-MS)同时检测103种农药的灵敏度,发现在NCI方式下103个化合物信噪比分别提高1.2~447.0倍。将GC-NCI/MS方法应用于蔬菜中103种农药的检测,检出限在0.06~13.1μg/kg之间,添加水平为20μg/kg和100μg/kg时,回收率在63.5%~123.8%之间,相对标准偏差为3.6%~13.3%。研究结果表明,相对于常用的GC-EI/MS检测方法,上述103个农药更适合采用NCI方式进行GC-MS同时分析。     

GC-NCI-MS衍生化法同时测定全血中的亚硝酸根和硝酸根

建立了全血中亚硝酸根（NO?22-）和硝酸根（NO?33-）的衍生化气相色谱－负化学电离源－质谱（GC－NCI－MS）定量分析方法。以同位素标记的15NO?22-和15NO?33-为内标,将全血中的NO?22-和NO?33-提取衍生后,对目标衍生物进行GC－NCI－MS分析。优化了目标物提取溶剂、衍生物提取溶剂、相转移试剂用量、衍生化方式、衍生化反应时间和温度,确定了最佳前处理条件。结果表明,全血中NO?22-在0.05～5 μg/mL范围内线性关系良好（r2 = 0.995）,检出限为0.01 μg/mL,准确度为89.6%～98.0%,日内和日间相对标准偏差（RSD）分别为1.8%～9.2%和2.1%～6.2%,提取回收率为99.8%～118%;NO?33-在1～300 μg/mL范围内线性关系良好（r2 = 0.997）,检出限为0.2 μg/mL,准确度为92.8%～112%,日内和日间RSD分别为0.60%～14%和0.60%～3.7%,提取回收率为80.3%～88.4%。应用该方法测得16份健康人体全血中内源性NO?22-和NO?33-的质量浓度分别为0.05～0.10 μg/mL和1.70～7.70 μg/mL。对真实亚硝酸盐中毒人体的全血进行测定,2种目标物的质量浓度远高于人体全血中内源性的浓度水平,可判定为亚硝酸盐中毒。该方法特异性强、灵敏度高,结果准确、可靠,能够满足亚硝酸盐中毒案件的检验鉴定需求。     

气相色谱法和液相色谱-串联质谱法测定水产品中敌敌畏残留量

建立了水产品中敌敌畏残留量检测的两种不同方法,比较了气相色谱(GC)与液相色谱-串联质谱(LC-MS/MS)检测方法的适用性。GC法检出限为3.0μg/kg,定量限为10.0μg/kg;LC-MS/MS法检出限为0.3μg/kg,定量限为1.0μg/kg。当敌敌畏添加水平在5.0~15.0μg/kg时,GC法方法回收率为75.0%~90.9%,相对标准偏差为2.8%~9.6%;LC-MS/MS法方法回收率为89.7%~98.1%,相对标准偏差为1.0%~5.0%。结果表明,应用GC与LC-M S/M S检测方法均能满足水产品中敌敌畏残留分析要求,但在不考虑实验成本的前提下,LC-MS/MS法更具有优势。     

气相色谱/质谱法测定鱼塘中的痕量硫丹

利用气相色谱/质谱(GC/MS),测定了鱼塘中痕量的硫丹,同时实现了硫丹的定性、定量.样品提取简便、高效,无需净化.用GC/MS的选择离子记录(SIR)方式测定低浓度硫丹的含量.硫丹在0.2～1000.0μg/mL范围内呈线性,该方法的检出限为0.086μg/mL,标准添加1.0、50μg/mL硫丹的回收率为87%、92%,测定的相对标准偏差为6.2%、13.1%.本方法能够满足痕量分析的实际要求.     

两种离子源技术GC/MS法检测蔬菜中多类除草剂的残留量

采用电子轰击(EI)和负化学(NCI)离子源两种离子源技术气相色谱-质谱联用法(GC-MS)测定了蔬菜中10类除草剂的残留量, 并对两种方法进行了比较. 样品经乙腈提取后, 用PSA固相萃取柱净化, 由气相色谱-质谱联用EI或NCI技术进行定量和定性分析. 对含电负性强的除草剂分析, NCI灵敏度高, 在10 ng/g, 20 ng/g和40 ng/g 3个添加水平下的方法回收率为70%～115%, RSD为1.7%～10.1%, 两种离子源技术可以互相补充用于准确检测蔬菜中多类除草剂.     

GC-MS/NCI稳定同位素稀释技术检测动物源性食品中氯霉素的残留量

建立了一种用于各种动物源性食品中氯霉素残留量的气相色谱-负化学离子源质谱(GC-MS/NCI)检测方法。以氘代氯霉素(D5-CAP)为内标物,用乙酸乙酯对各类样品中的氯霉素进行提取,用正己烷和40 g/L NaCl溶液液液分配除脂肪,基质复杂的样品再用Oasi HLB固相萃取柱净化,经硅烷化衍生后由GC-MS/NCI在选择离子监测模式下进行测定。多数样品在0.2,0.5,1.0μg/kg3个添加水平下氯霉素的回收率处于87.8%和107.0%之间,相对标准偏差(RSD)不大于8.5%。方法在2.0~80.0μg/L范围内有良好的线性关系,基质复杂样品中氯霉素残留的检出限达到0.1μg/kg,基质简单样品的检测限可达0.05μg/kg。方法适合各种动物源性食品中氯霉素残留量的确证分析。     

SPME/GC法测定油炸淀粉类食品中的丙烯酰胺

自制了十六醇/聚己二酸乙二醇酯(CA/PGA)固相微萃取探头,建立了油炸淀粉类食品中丙稀酰胺的SPME/GC测定方法。利用该方法测定了油炸方便面和油条中的丙烯酰胺。结果显示,SPME/GC法在2.5μg/kg~1500μg/kg范围内有很好的线性,检测限为2.5μg/kg,回收率为91.2%~98.8%,RSD为2.7%(n=6)。该法比传统的LLE溴衍生化/GC法灵敏度高,重现性好,操作简便。     

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%.     

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.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.