HPLC测定动物组织中己烯雌酚、呋喃唑酮、磺胺类药物残留

建立了用于动物组织中己烯雌酚、呋喃唑酮、磺胺甲氧嘧啶、磺胺二甲嘧啶、磺胺间甲嘧啶、磺胺甲唑、磺胺喹啉残留测定的高效液相色谱法。样品以乙腈提取,正己烷脱脂,SPE(AluminaB)净化,分步溶剂洗脱,HypersilODSC18(4.6×250mm,5μm)进行分离,紫外检测器检测,梯度洗脱测定五种磺胺,通过波长在线切换测定己烯雌酚和呋喃唑酮。回收率在89.2%～98.6%,相对标准偏差为3.2%～5.1%,己烯雌酚、呋喃唑酮和磺胺的最低检测限分别为0.5、0.1和0.2ng。该方法已成功应用于禽类样品的兽药多残留的检测。     

固相萃取–高效液相色谱法同时测定饲料中4种磺胺类药物残留

建立固相萃取–高效液相色谱法同时测定饲料中的磺胺嘧啶、磺胺二甲嘧啶、磺胺甲恶唑、磺胺喹恶啉4种磺胺类药物残留的方法。样品用乙腈提取,然后用碱性氧化铝固相萃取柱净化,色谱柱为C_(18)柱(250 mm×4.6mm,5μm),以水–乙腈(体积比为75∶25,含0.3%乙酸)为流动相,流量为1.0 mL/min,检测波长为270 nm。4种磺胺类药物的质量浓度在1~10μg/mL范围内与其色谱峰面积呈良好的线性,相关系数均大于0.999,检出限为0.025~0.133μg/g。磺胺类药物测定结果的相对标准偏差为0.22%~0.30%(n=6),样品加标回收率为93.6%~106.7%。实际饲料样品中均未检出这4种磺胺组分。该方法具有干扰少,灵敏度高,重复性好的优点,可以作为饲料中的磺胺类药物残留的一种检测方法。     

UPLC法检测渔用饲料中八种磺胺类药物残留的研究

本文通过对多组样品的试验测定,建立了一种渔用饲料中8种常用磺胺(磺胺嘧啶、磺胺甲基嘧啶、磺胺二甲基嘧啶、磺胺噻唑、磺胺甲基异噁唑、磺胺多辛、磺胺异噁唑和磺胺喹噁啉)的超高效液相色谱检测法。具体是:样品经2%乙酸浸润,4℃预冷的乙腈提取,碱性氧化铝柱净化,用Symmetry-C18色谱柱(5μm,4.6×150mm),2%乙酸-甲醇梯度洗脱,紫外检测,检测波长270nm。结果表明,8种磺胺的定量底限为2mg/kg,在0.5~20μg/m L内,线性关系良好,R20.99。添加水平10mg/kg时,8种磺胺类药物的平均回收率范围为70%~100%,RSD15。该方法回收率高,简单,准确可靠,可用于渔用饲料中磺胺类药物残留的监测。     

超高效液相色谱-四极杆飞行时间质谱法快速筛查生鲜牛乳中的14种磺胺类药物

采用超高效液相色谱-四极杆飞行时间高分辨质谱(UHPLC-Q TOF MS)技术建立了生鲜牛乳中14种磺胺类药物(磺胺二甲嘧啶、磺胺嘧啶、磺胺二甲氧嘧啶、磺胺噻唑、磺胺吡啶、磺胺氯哒嗪、磺胺甲嘧啶、磺胺醋酰、磺胺曲沙唑、磺胺苯吡唑、磺胺苯酰、磺胺甲噻二唑、磺胺甲氧哒嗪、磺胺甲唑)的快速筛查方法。建立了此14种化合物的精确分子质量数和二级质谱碎片离子数据库。牛乳样品经含0.1%甲酸的乙腈溶液提取,采用Qu ECh ERS方法净化。目标药物经Agilent ZORBAX SB C18色谱柱(3.0 mm×100 mm,1.8μm)分离,以乙腈-0.1%甲酸水溶液为流动相进行梯度洗脱,使用Dual AJS ESI源,在正离子模式下进行数据采集,可在8 min内实现对14种磺胺类药物的良好分离。结果表明,14种磺胺类药物的定量下限(LOQ,S/N=10)为10μg/kg,在10,20,50μg/kg 3个加标水平下的平均回收率为72.5%~117.1%,相对标准偏差为1.3%~10.9%。结合精确分子质量数、保留时间、同位素丰度和二级特征碎片离子对目标化合物进行快速筛查与确证。该方法快速简便、准确、灵敏度较高,适用于牛乳中磺胺类药物残留的高通量筛查与定性鉴定。     

高效液相色谱-串联质谱法测定兽药粉剂中18种磺胺类违禁添加药物

建立了非磺胺类兽药粉剂中磺胺二甲嘧啶、磺胺醋酰、磺胺甲噻二唑、磺胺氯哒嗪、磺胺甲基异唑、磺胺噻唑、磺胺-6-甲氧嘧啶、磺胺甲基嘧啶、磺胺邻二甲氧嘧啶、磺胺吡啶、磺胺对甲氧嘧啶、磺胺甲氧哒嗪、磺胺苯吡唑、磺胺间二甲氧嘧啶、磺胺二甲异唑、磺胺喹啉、磺胺嘧啶、甲氧苄氨嘧啶18种磺胺及其增效剂等违禁添加药物的超高效液相色谱-串联质谱分析方法。样品经甲醇-水(90∶10)萃取后,以乙腈(含0.1%甲酸)和水(含0.1%甲酸)为流动相,C18(2.1 mm×150 mm,5μm)色谱柱分离后,在正离子模式下以电喷雾串联质谱仪进行测定。方法的线性范围为50~2 000μg/kg,18种磺胺类药物残留的检出限为10μg/kg。在50,200,1 000μg/kg 3个浓度水平下进行加标回收实验,平均回收率为86.8%~115%,相对标准偏差为1.0%~9.7%。     

牛奶中12种磺胺类药物残留的高效液相色谱测定方法

建立了高效液相色谱(HPLC)检测牛奶中12种磺胺类药物(磺胺二甲基嘧啶、磺胺间甲氧嘧啶、磺胺甲噁唑、磺胺对甲氧嘧啶、磺胺喹噁啉、磺胺氯哒嗪、磺胺氯吡嗪、磺胺嘧啶、磺胺噻唑、磺胺甲基嘧啶、磺胺甲噻二唑、磺胺地索辛)残留的方法,考察了样品的提取、净化及色谱分析条件。牛奶样经乙酸乙酯提取、固相萃取净化后上机分析,11种磺胺药物标准曲线在10~800μg/L,SM2在5~200μg/L质量浓度范围内相关系数r>0.999,回收率为76%~106%,相对标准偏差小于15.9%。检出限为5~8μg/L,定量下限为14~27μg/L。     

高效液相色谱法同时测定动物源性食品中5种磺胺及3种四环素族抗生素残留

建立了动物源性食品中5种常用磺胺(磺胺甲噁唑、磺胺2甲氧嘧啶、磺胺二甲基嘧啶、磺胺-6甲氧嘧啶、磺胺喹噁啉)及3种四环素族(土霉素、金霉素、四环素)抗生素残留的高效液相色谱同时测定方法.样品经提取,固相萃取净化,浓缩后进行HPLC分离,结合保留时间及二极管阵列检测器(PDA)光谱分析信息定性.添加水平为20、50、100μg/kg时5种磺胺及3种四环素族的平均回收率范围为70%~92%,变异系数小于15%.结果表明,该法简单、快速、灵敏,适用于动物源性食品中多磺胺组份及四环素族组份残留的同时测定.     

超高效液相色谱-串联质谱法同时测定化妆品中的22种磺胺类药物

建立了同时测定化妆品中22种磺胺类药物(磺胺胍、磺胺、磺胺嘧啶、磺胺二甲异嘧啶、磺胺醋酰、磺胺噻唑、磺胺吡啶、磺胺甲基嘧啶、磺胺对甲氧嘧啶、磺胺二甲噁唑、磺胺二甲嘧啶、磺胺甲噻二唑、磺胺甲氧哒嗪、琥珀酰磺胺噻唑、磺胺氯哒嗪、磺胺甲基异噁唑、磺胺间甲氧嘧啶、磺胺邻二甲氧嘧啶、磺胺二甲异噁唑、磺胺间二甲氧嘧啶、磺胺喹噁啉、磺胺硝苯)的超高效液相色谱-串联质谱分析方法。膏霜、水剂、散粉、香波、唇膏等不同类型的化妆品样品经超声提取后,以Waters ACQUITY UPLC BEH C18色谱柱(50 mm×2.1 mm,1.7μm)分离后进行UPLC/MS/MS多反应监测模式下的定性及定量分析。22种磺胺类药物的方法检出限为3.5~14.1μg/kg;在低、中、高的3个添加水平范围内的平均回收率为80.3%~103.6%;日内精密度均小于12%,日间精密度均小于15%。     

固相萃取-高效液相色谱法测定水果中单甲脒的残留量

建立了固相萃取-高效液相色谱法(SPE-HPLC)测定水果中农药单甲脒残留量的检测方法.用HCl溶液将样品中单甲脒转化为盐酸盐并溶于水中,在碱性条件下用乙腈提取,经碱性氧化铝固相萃取柱净化.采用C18柱(250 mm×4.6 mm,5 μm)分离,以甲醇-0.01 mol/L乙酸铵溶液(50∶ 50, V/V)为流动相,在254 nm下检测.本方法可以将单甲脒与基质良好分离,在0.01～10 mg/L浓度范围内线性良好(R2=0.9999);检出浓度为0.0013 mg/kg,回收率为80.7%～95.3%,相对标准偏差小于7%,可用于水果中单甲脒残留量的检测.     

分子印迹固相萃取-超高效液相色谱串联质谱法测定猪肉中磺胺二甲氧嗪EI北大核心CSCD

建立了基于分子印迹聚合物(MIPs)为固相萃取填料的固相萃取技术结合超高效液相色谱串联质谱法(MISPE-UPLC-MS/MS)检测猪肉中磺胺二甲氧嗪。以磺胺二甲氧嗪为模板分子,三氟甲基丙烯酸为功能单体,采用沉淀聚合法制备了分子印迹固相萃取填料,并对萃取净化条件进行了优化。在优化的提取条件和分析条件下,对猪肉肌肉样品中磺胺二甲氧嗪进行分析,其检出限为1.225μg/kg;定量限为4.083μg/kg;双水平回收率在81.4%~106.9%;RSD为3.7%和12%。与M CX柱净化相比,分子印迹固相萃取柱能够有效去除基质效应,分离待测物与杂质。     

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.