高效液相色谱法测定高含水量辣椒制品中的辣椒素类物质

样品以70%乙醇提取,采用反相高效液相色谱分离,色谱条件:色谱柱ZORBAX SB C184.6 mm×250mm,5μm;流动相为甲醇-水(体积比70∶30);流速0.8 mL/min;UV230 nm检测;进样量20μL。以外标峰面积法定量辣椒素(C)、二氢辣椒素(DC)、去甲二氢辣椒素(NDC),结果以斯氏指数(SHU)计。NDC的色谱行为与C极其类似,NDC采用C的标准曲线定量。C和DC的RSD分别为1.0%、1.5%(n=5);平均回收率分别为97%、96%。C和DC在0.001~0.1 g/L范围内线性良好;检出限(LOD)为0.1 mg/L,定量下限(LOQ)为0.5 mg/L。方法满足辣味水平评价要求。     

超高效液相色谱法快速测定辣椒素类物质

建立了超高效液相色谱法快速测定辣椒制品中辣椒素、二氢辣椒素、降二氢辣椒素的方法.样品以四氢呋喃-甲醇(体积比1:1)提取,采用反相高效液相色谱分离.色谱柱为BEH C18,流动相乙腈-水进行梯度洗脱;二极管阵列检测器(DAD),检测波长为280 nm.各成分在1.0 -100.0 mL/L范围内线性良好.辣椒素、二氢辣...     

高效液相色谱柱后衍生测定鸡组织中甲基盐霉素残留量

建立了鸡组织中甲基盐霉素的高效液相色谱柱后衍生化分析方法.样品经异辛烷提取,离心后上层有机相过硅胶固相萃取小柱,洗脱液浓缩后用V(甲醇)∶ V(水)=90∶ 10混合液溶解.采用Inertsil ODS-3 C18柱,以V(甲醇): V(乙酸)∶ V(水)=94∶ 3∶ 3为流动相,香草醛为衍生剂进行高效液相色谱柱后衍生分析,520 nm检测,外标法定量.方法检出限为6 μg/kg; 定量限为20 μg/kg; 添加浓度在20～1800 μg/kg范围内,平均添加回收率为76.4%～93.1%; 批内相对标准偏差(RSD)在2.6%～8.9%之间; 批间相对标准偏差(RSD)在4.7%～9.7%之间.样品浓度在0.07～10.0 mg/L范围内与峰面积呈良好的线性关系,r>0.9993.     

制备型高效液相色谱法制备纯化3种辣椒素单体

利用制备型反相高效液相色谱法从辣椒素类物质中制备了3种辣椒素单体。在PRC-ODS色谱柱(250 mm×21.5 mm,13 μm)上,以甲 醇-水(体积比为70∶30)为流动相,流速为15 mL/min,采用等度洗脱方式,从80%的辣椒素类物质中制备了3种辣椒素单体。经核磁共振 氢谱(1H NMR)及电子轰击离子源质谱(EI-MS)分析,确认它们分别为降二氢辣椒素、辣椒素和二氢辣椒素,收率分别为60.1%,58.9%和 72.3%。高效液相色谱分析表明所制备的3种化合物的纯度分别达到了98.12%,99.93%及100.7%。     

反相高效液相色谱法同时测定黄连中巴马亭及小檗碱的含量

采用反相高效液相色谱法同时测定黄连中巴马亭及小檗碱的含量,色谱条件:ODSC18色谱柱(4.6mm×250mm);流动相为乙腈∶0.05mol/L磷酸二氢钠水溶液(pH2.5)=30∶70(V/V);流速0.6mL/min;测定波长268nm.巴马亭和小檗碱的回归方程分别为C=1.696×10-5A+0.8401,R2=0.9999;RSD=0.015%和C=1 580×10-5A+0.5114,R2=0.9999,RSD=0.14%.回收率分别为99.09%～101.30%和98.96%～101.86%.此方法准确、快速、简单.     

GPC–HPLC–MS/MS法测定食用油中天然辣椒素、二氢辣椒素和合成辣椒素含量

以动植物油脂为实验材料,建立了测定食用油中天然辣椒素、二氢辣椒素和合成辣椒素含量的凝胶渗透色谱–高效液相色谱–串联质谱(GPC–HPLC–MS/MS)法。样品经凝胶渗透色谱净化后,采用液相色谱串联质谱法(HPLC–ESI–MS/MS)分析,多反应监测模式(MRM)下外标法定量。在0.1~5.0μg/L范围内线性良好,天然辣椒素、二氢辣椒素和合成辣椒素的相关系数分别为0.999 6,0.999 8,0.999 8,检出限为0.5μg/kg。在5μg/kg添加水平下,空白加标回收率为71.5%~82.5%,测定结果的相对标准偏差为3.0%~8.3%(n=6)。该方法样品处理过程简便快捷,测定结果准确,可满足实验室大量、快速分析的需求。     

高效液相色谱法同时测定诺诺感冒片中扑尔敏、扑热息痛、盐酸伪麻黄碱的含量

 采用反相高效液相色谱法 ,在C18柱上以V(甲醇 )∶V(水 ) =2 5∶75的溶液为流动相 (内含 0 .0 5mol/L磷酸二氢钠 ) ,检测波长为 2 0 5nm ,同时分离测定诺诺感冒片中扑尔敏、扑热息痛、盐酸伪麻黄碱的含量。扑尔敏、扑热息痛和盐酸伪麻黄碱的检出限分别为 1.16mg/L ,0 .15mg/L和 1.82mg/L ,其相应的回收率分别为 98.35 % (n =5 ,RSD =1.6 0 % ) ,10 1.16 % (n =5 ,RSD =1.5 0 % )和 98.5 0 % (n =5 ,RSD =1.5 9% )。方法简便、快速 ,重现性好 ,适用于诺诺感冒片的质量检验分析。     

高效液相色谱法测定涂料中乙酸苯基汞防霉剂

建立了高效液相色谱法对涂料中乙酸苯基汞进行检测的方法.样品经稀释后,以V(乙腈)∶V(2 mmoL NH4Ac)=90∶10为流动相,C18柱高效液相色谱分离,DAD为检测器,检测波长为195 nm.结果表明,线性范围为0.1～10 mg/L(相关系数r2=0.9995),检出限为0.097 mg/L(相当于涂料中质量分数为2.43×10-3%),对涂料样品进行5个不同浓度水平的添加回收,回收率为97.3%～103.1%,RSD≤4.5%(n=7).本法具有较高的选择性、灵敏度和准确度,能满足涂料中乙酸苯基汞的测定分析.     

发用防晒剂DDABDT的反相高效液相色谱法测定

建立了反相高效液相色谱法测定发用防晒剂二甲基对胺基苯甲酰胺丙基十二烷基二甲胺甲苯磺酸盐(简称DDABDT)的方法.采用的色谱条件为色谱柱Symmetry C8柱,流动相为V(乙腈):V(10 mmol/L NaAc)=65:35溶液(含体积分数0.02%三氟乙酸,pH5.04),流速1.0 mL/min;检测波长305 nm;进样量20μL.DDABDT质量浓度为0.05～1000 mg/L时,其浓度与峰面积呈良好的线性关系(R2＞0.999),检出限为0.02 mg/L(S/N=3).洗发水A中DDABDT的回收率在98.0%～102%之间,发样提取液中DDABDT的平均回收率在85%～108%之间.洗发水中DDABDT浓度测定日内和日间相对标准分别为1.2%,3.4%.头发吸附DDABDT含量测定日内和日间相对标准偏差(RSD)分别为9.1%,9.8%.同时以高效液相色谱-电喷雾离子化质谱对色谱法测定样品的DDABDT峰进行了验证.该方法已用于洗发水及头发吸附DDABDT的分析.     

高效液相色谱法同时测定血清和尿中厚朴酚与和厚朴酚

 建立了大鼠服用厚朴提取物后的血清中及尿中厚朴酚与和厚朴酚的高效液相色谱测定法。色谱柱填料为SpherisorbC18,流动相为甲醇-水-冰醋酸(体积比为70∶30∶1),UV检测波长为294nm,灵敏度0.005AUFS。样品用甲醇沉淀蛋白,上清液酸化后用乙酸乙酯-乙醚萃取,然后测定其中的药物浓度。血清和尿中的药物浓度与峰面积的线性关系良好,线性范围分别为0.05～2mg/L(厚朴酚)、0.025～1mg/L(和厚朴酚);精密度和重现性良好。血清中厚朴酚与和厚朴酚的平均加样回收率分别为95.6%(RSD=3.85%)和93.8%(RSD=3.95%),尿中分别为96.0%(RSD=3.83%)和94.9%(RSD=3.54%)。     

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.