高效液相色谱法测定双氯芬酸钠凝胶的有关物质

建立了双氯芬酸钠凝胶中有关物质的高效液相色谱分离分析方法。采用梯度洗脱的方法对双氯芬酸钠凝胶的有关物质进行分离,流动相A为pH 2.0三氟乙酸溶液-甲醇(80:20),流动相B为乙腈-甲醇(80:20)。采用Waters XBridge色谱柱(5μm,150mm×4.6mm)进行分离,流速为1.0mL/min,进样体积为5μL,二极管阵列检测器,检测波长为254nm,柱温为30℃。在上述色谱条件下,双氯芬酸钠凝胶及特定杂质均在1.0～40.0mg/L质量浓度范围内线性关系良好,相关系数(r)均大于0.99;方法对特定杂质的回收率为97%～104%,相对标准偏差(RSD)不大于3.8%。该法简便、快速、准确、选择性好、灵敏度高,可用于含醇类辅料的双氯芬酸钠凝胶中有关物质的检测。     

中空纤维膜液相微萃取-高效液相色谱法测定醋酸氯己定痔疮栓中的醋酸氯己定

建立了中空纤维膜液相微萃取-高效液相色谱（HPLC）测定醋酸氯己定痔疮栓中醋酸氯己定含量的方法。将样品用醋酸水溶液萃取5次,配成样品溶液,然后用装有正辛醇的中空纤维膜进行液相微萃取,萃取液用高效液相色谱测定。醋酸氯己定的质量浓度为0.5 ～ 16 mg/L时与其峰面积呈良好的线性关系,加样回收率大于98.0%,相对标准偏差低于4.0%。该方法样品处理简单、快速,灵敏度与不经过液相微萃取的HPLC方法相比提高了约24倍,醋酸氯己定痔疮栓中的其他物质对测定无干扰。     

中空纤维离心超滤-高效凝胶排阻色谱法测定青霉素V钾中蛋白杂质

建立了一种采用中空纤维离心超滤(HFCF-UF)-高效凝胶排阻色谱法(HPSEC)对青霉素V钾中的残留蛋白进行检测的方法。样品用HFCF-UF进行富集,采用HPSEC进行分析,色谱柱为TSK gel Super SW2000凝胶色谱柱(300×4.6mm,4μm),流动相为0.06mol/L NaCl-0.02mol/L NaH_2PO_4(pH=7.0),流速为0.3mL/min,紫外检测波长为220nm,柱温为室温。对照品牛血清白蛋白(BSA)在1.0~100.0μg/mL内线性关系良好(R2=0.999),回收率均大于87%,检测限为3.03ng/mL,经HFCF-UF富集处理后,富集倍数(EF)高达99倍。结果表明,该方法操作简便、结果准确、灵敏度高,为同类药物中的大分子蛋白检测提供了有效手段。     

中空纤维分离-高效液相色谱法测定静脉注射用人免疫球蛋白中的麦芽糖

建立了中空纤维分离-HPLC测定静脉注射用人免疫球蛋白中的麦芽糖含量的方法.在离心力的作用下,样品溶液中的小分子物质能透过垂直放置在离心管中的中空纤维,同时离心力也减小了膜外大分子形成的浓差极化.采用Inertsil NH2色谱柱(250 mm×4.6 mm,5 μm)及示差折光检测器,流动相为V(乙腈)∶V(水)=70∶ 30,柱温40 ℃,流速为1.0 mL/min.麦芽糖浓度在1.00～5.00 g/L范围内线性关系良好(r=0.9999),平均加标回收率为100.6%,RSD为1.4%.本方法简便快速、结果准确,克服了蛋白沉淀不完全,吸附严重等现象,为微量样品的分析提供了简单廉价超滤手段,适用于蛋白类制品小分子样品的前处理.     

气相色谱-质谱法测定血浆中双氯芬酸钠的含量

提出了应用气相色谱-质谱法测定血浆中双氯芬酸钠含量。血浆样品中双氯芬酸钠经盐酸提取,并加入三甲基硅烷衍生化试剂进行衍生化,所得衍生化产物经萃取、净化后供气相色谱分离及质谱测定。采用选择离子质谱扫描方式,供试品双氯芬酸钠-三甲基硅烷衍生物定量选择离子检测质荷比为m/z367,内标物布洛芬-三甲基硅烷衍生物定量选择离子检测质荷比为m/z263。双氯芬酸钠的线性范围为0.005～5.0mg·mL-1,检出限(3S/N)为0.5μg.L-1。方法回收率在94.6%～97.4%之间,日内、日间相对标准偏差(n=6)均小于5%。     

接枝中空纤维膜过滤-液相色谱/串联质谱法检测血浆中盐酸克伦特罗

建立了接枝改性的中空纤维膜过滤法净化处理-液相色谱-串联质谱法(LC-MS/MS)测定血浆中痕量盐酸克伦特罗的方法。血浆样品经改性中空纤维膜的过滤,通过膜上接枝的离子交换基团的吸附作用和膜孔的超滤作用去除其中的磷脂和蛋白质,消除了基质效应,提高了LC-MS/MS检测盐酸克伦特罗的灵敏度。色谱条件为:色谱柱采用Venusil MP C18(2.1×50 mm,3μm,10 nm),流动相为乙腈/0.1%甲酸水溶液(15:85,V/V),流速为200μL/min,柱温30℃,进样量5μL。质谱模式为电喷雾电离正模式。在1~100 ng/m L范围内,线性关系良好;检出限为0.21 ng/m L,回收率在90%~105%之间,RSD为3.8%~9.1%。方法适合血浆样品中痕量盐酸克伦特罗的检测。     

超高效液相色谱-串联质谱法测定大鼠血浆中托品酸浓度

建立测定大鼠血浆中托品酸浓度的超高效液相色谱-串联质谱法。以双氯芬酸钠作为内标,采用Phenomenex Luna C_(18)色谱柱,流动相为0.1%甲酸水-乙腈溶液,运行时间为4.5 min,梯度洗脱,流速为0.3 mL/min,进样量为5μL,柱温40℃。样品经大气压力化学离子源负离子化后,通过三重四极杆串联质谱仪,在多反应监测模式下测定托品酸(m/z 164.93→102.93)和内标双氯芬酸钠(m/z 293.97→214.01)的浓度。血浆样品前处理采用甲醇沉淀蛋白。结果表明,托品酸的血浆浓度在40～25000 ng/mL内线性良好,定量下限为40 ng/mL,批内、批间精密度(RSDs)均在1.2%～6.7%以内,准确度(RE)在96.4%～113.8%以内。血浆样品室温放置6 h,样本处理后室温放置8 h,反复冻融3次及冰冻(-20℃)保存7 d的情况下均稳定。本方法适用于大鼠血浆中托品酸浓度的测定,也可为临床浓度监测提供依据。     

三相中空纤维式液相微萃取用于快速富集血浆中的尼古丁

建立了一种以三相中空纤维式液相微萃取(TP-HF-LPME)进行样品前处理,采用高效液相色谱快速、准确测定血浆中尼古丁含量的方法。研究表明该方法集萃取、富集、净化为一步,极大地简化了传统血浆成分测定的前处理过程,是一种快速、有效、绿色的前处理方法。方法的线性范围为0.1～50 mg/L,相关系数(r2)为0.9996,检测限为0.05 mg/L (信噪比为3),相对标准偏差小于5%。     

壳聚糖/多壁碳纳米管修饰石墨电极-流动注射双安培法测定双氯芬酸钠

制备了壳聚糖/多壁碳纳米管修饰石墨电极(记为CS-MCNT′s/GE),并采用循环伏安法研究了双氯芬酸钠在该修饰电极上的电化学行为。基于双氯芬酸钠在CS-MCNT′s/GE上的催化氧化和不可逆电对的双安培检测原理,通过偶合双氯芬酸钠的氧化和MnO4-在铂电极上的还原两个不可逆电极过程,提出了流动注射双安培法直接测定双氯芬酸钠浓度的方法。在pH 6.8的磷酸盐缓冲溶液中,外加电位差为0 V时,双氯芬酸钠的峰电流与其浓度在8.0×10-7～2.0×10-4mol.L-1范围内呈线性关系,检出限(3S/N)为2.0×10-7mol.L-1。连续测定1.0×10-5mol.L-1双氯芬酸钠标准溶液20次,相对标准偏差为4.75%,以双氯芬酸钠片为基底,加标回收率在98.0%～105.5%之间。     

可忽略损耗液相微萃取法同时测定辛醇-水分配系数和电离常数

以4-氯酚(4-CP)、2,4-二氯酚(2,4-DCP)和2,4,6-三氯酚(2,4,6-TCP)为模型化合物,建立了中空纤维膜支载-可忽略损耗液相微萃取法(HF-nd-LPME)和高效液相色谱(HPLC)联用,同时测定辛醇-水分配系数(Kow)和电离常数(pKa)的方法。在60 mL正辛醇饱和的样品溶液(1mmol/L NaH2PO4,2μg/mL4-CP、2,4-DCP和2,4,6-TCP)中放入2个支载有0.16μL正辛醇的中空纤维膜萃取装置,静置96 h确保达到萃取平衡。然后将萃取装置取出并用甲醇解吸,经HPLC测定得到萃取到正辛醇中的目标物浓度coctanol。coctanol与样品中目标物原始浓度cwater的比值即为Kow。通过测定模型化合物在不同pH3.0~13条件下的Kow值,并依据化合物的Kow、pKa与pH的关系模型进行非线性拟合,即可计算得出模型化合物pKa值。实验表明,本方法测定的三种模型化合物的Kow和pKa值与文献报道值一致。     

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.