高效液相色谱法测定果蔬中多种苯甲酰脲类农药残留

建立用高效液相色谱法测定果蔬中10种苯甲酰脲类农药残留量的检测方法。采用微量化学法和固相萃取技术,高效液相色谱法测定。本方法最低检测限为0.02~0.03mg/kg,样品在添加浓度为0.05~0.2mg/kg时,平均回收率为70.4%~107.5%。     

高效液相色谱/质谱法测定土壤中10种磺酰脲类除草剂多残留

建立了高效液相色谱/质谱法(HPLC-MS)同时检测土壤中10种磺酰脲类除草剂多残留量的方法。样品在磷酸缓冲液(pH值7.8):甲醇(8∶2,V/V)中经超声波萃取,提取液直接经固相萃取小柱净化,采用HPLC-ESI( )-MS进行定性定量分析。比较了C leanert C18,C leannertHXN和Oasis HLB 3种SPE商品柱的净化效果,结果表明C leanert C18和C leannertHXN柱的净化效果和回收率均较好。10种磺酰脲类农药的液相色谱分离在乙腈-甲醇-水(0.2%冰醋酸)梯度洗脱下完成,10个化合物的保留时间在10~16 m in。10种磺酰脲类除草剂在0.1~10.0 mg/L范围内线性良好,相关系数均在0.9964~0.9989之间;相对标准偏差在0.99%~4.26%之间。在0.01~1.0 mg/kg添加水平范围内,平均添加回收率在80.2%~104.5%之间(除苯磺隆)。本方法中10种磺酰脲类除草剂在土壤中的检出限为0.6~3.5μg/kg之间。     

分子印迹固相萃取-高效液相色谱法同时检测烟叶中磺酰脲类农药残留

以氯磺隆（CS）为模板分子,甲基丙烯酸为功能单体,三羟甲基丙烷三甲基丙烯酸酯为交联剂,在二氯甲烷氛围中,经沉淀聚合制备氯磺隆分子印迹聚合物（CS-MIP）微球。将该聚合物微球作为填料制得分子印迹固相萃取柱用于样品前处理,建立了分子印迹固相萃取-高效液相色谱（MIP-SPE-HPLC）同时检测烟叶中6种磺酰脲类除草剂残留的分析方法。针对氯磺隆、甲磺隆、苄嘧磺隆、苯磺隆、胺苯磺隆和烟嘧磺隆6种磺酰脲类除草剂,在烟叶中加标0.50~50 μg/g,经氯磺隆分子印迹固相萃取柱（CS-MIP-SPE）净化和富集,高效液相色谱（HPLC）检测,其平均回收率为77.60%~102.05%,相对标准偏差为0.16%~7.07%,检出限为0.08~0.46 μg/g。将MIP-SPE-HPLC方法用于实际农药残留检测,结果表明可同时满足烟叶中多种磺酰脲类除草剂残留量的检测要求。     

固相萃取-高效液相色谱法同时检测大米中12种磺酰脲类除草剂的残留

建立了固相萃取前处理净化技术-高效液相色谱（HPLC）同时检测大米中12种磺酰脲类除草剂残留的方法。采用ENVITM-18(C18)硅胶柱和ENVI-Carb(GCB)石墨化碳柱对样品进行净化、萃取,采用C8柱,以乙腈和5 mmol/L 冰乙酸混合溶剂为流动相进行梯度洗脱,在240 nm下进行检测。12种磺酰脲类除草剂在0.01~0.50 μg/g添加范围内的回收率为72.2%~106.5%,相对标准偏差为0.6%~6.4%,检出限为0.01~0.02 μg/g。     

基于十八烷基三甲基溴化铵修饰的磁性粒子在线磁性固相萃取-高效液相色谱法测定水样中磺酰脲类农药

采用溶胶-凝胶法制备表面修饰了十八烷基三甲基溴化铵的磁性粒子作为萃取剂，研制了一种在线磁性固相萃取（on-line MSPE）装置，建立了on-line MSPE与高效液相色谱联用测定水样中两种磺酰脲类农药（氯磺隆、苄嘧磺隆）的方法。实验优化了在线磁性固相萃取条件并进行方法学考察，证明该方法具有良好的线性关系（两种目标物的线性相关系数均≥ 0.9997）和较低的检出限（两种目标物的检出限分别为0.32和1.12 μg/L）。将此法用于3种环境水样中两种磺酰脲类农药的检测，水样中均检出氯磺隆，均未检出苄嘧磺隆。两种目标物加标回收率为70.0%~113.4%。该方法高效、简便，在分离富集环境水样中磺酰脲类农药方面有一定的应用前景。     

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。     

MIL-53(Fe)@聚多巴胺@Fe_3O_4磁性复合材料的制备及其用于环境水样中磺酰脲类除草剂的磁固相萃取

制备了MIL-53(Fe)和聚多巴胺(PDA)修饰的磁性Fe_3O_4复合材料MIL-53(Fe)@PDA@Fe_3O_4,并将其作为吸附剂用于磁固相萃取-高效液相色谱法(MSPE-HPLC)检测环境水样中4种磺酰脲类除草剂(甲嘧磺隆、苄嘧磺隆、吡嘧磺隆和氯嘧磺隆)。实验优化了高效液相色谱条件(乙腈和含0.01%(体积分数)三氟乙酸的水溶液为流动相进行梯度洗脱,检测波长为233 nm)及磁固相萃取条件(洗脱剂为5 mL丙酮,萃取时间为4.5 min,吸附剂用量为60 mg,NaCl加入量为0.5 g,溶液pH值为3),在最佳条件下进行方法学考察,4种磺酰脲类除草剂均得到良好的线性关系,相关系数(r)≥0.998 0。方法的检出限(LOD,S/N=3)为0.28~0.77μg/L。将建立的方法用于3种环境水样中4种磺酰脲类除草剂的检测,其加标回收率为78.8%~109.7%。结果表明,制备的功能化复合材料结合了MIL-53(Fe)和Fe_3O_4的优点,可以简便快速地萃取分离环境水样中磺酰脲类除草剂。     

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。     

高效液相色谱-串联质谱法同时测定茶汤中7种苯甲酰脲类农药残留

建立了高效液相色谱-串联质谱(HPLC-MS/MS)法,结合溶剂提取和固相富集技术同时测定茶汤中氟啶脲、除虫脲、啶蜱脲、氟虫脲、氟铃脲、伏虫隆和杀铃脲7种苯甲酰农药残留的方法。研究了提取溶剂的种类、用量和提取时间,以及固相富集小柱的固定相和流动相对7种苯甲酰脲类农药的提取率、分离度、灵敏度和重现性等的影响。结果表明,在最佳条件下,7种苯甲酰脲类农药在6.5min内被完全分离。7种苯甲酰脲类农药残留的检测限(DL)和定量限(QL)分别为0.08~1.00ng/mL和0.09~3.02ng/mL,加标回收率为90%~105%,相对标准偏差(RSD)小于7%(n=6)。利用所建立的方法成功测定了不同茶汤中上述7种苯甲酰脲类农药残留。该方法具有耗时短、灵敏度高、稳定性好等优点,有助于茶叶安全饮用的准确评价。     

固相萃取/高效液相色谱法同时测定保健食品中7种磺酰脲类降血糖药物

建立了同时测定保健食品中7种磺酰脲类降血糖药物(格列吡嗪、甲苯磺丁脲、妥拉磺脲、格列齐特、格列本脲、格列美脲和格列喹酮)的固相萃取/高效液相色谱(SPE/HPLC)分析方法。样品经甲醇超声提取,用C18固相萃取柱净化后进行HPLC分析。采用Agilent Zorbax SB-C18色谱柱(250 mm×4.6 mm,5μm),以乙腈(A)-0.02%磷酸溶液(B)为流动相,梯度洗脱,流速1.0 mL/min,柱温30℃,检测波长228 nm。结果表明,7种目标物在0.2~20μg/mL范围内线性关系良好,相关系数(r)大于0.999 9,检出限(LOD,S/N≥3)均为0.1 mg/kg,在5种不同基质中的加标回收率为81%~115%,相对标准偏差(RSD)小于9%。     

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.