单糖的柱前衍生化高效液相色谱及胶束电动毛细管色谱分析的对比研究

 采用1-苯基-3-甲基-5-吡唑啉酮(PMP)衍生糖类物质,通过简化衍生方法,优化分析条件,采用胶束电动毛细管色谱(MEKC)和高效液相色谱(HPLC)两种方法对5种还原单糖的PMP衍生物实现了良好的分离。5种还原单糖衍生物的保留时间的重现性较好(MEKC法的相对标准偏差(RSD)小于5%(n=5),HPLC法的RSD为0.23%(n=5))。用所建立的两种方法对实际样品中的糖进行了分析,结果表明所建方法可作为实际样品中单糖分析的常规方法。     

糖类化合物PMP衍生分析进展

糖类物质的结构与组成分析在揭示其生物学功能方面发挥着重要作用,糖类化合物的衍生化分析是实现其高灵敏度定性和定量检测的有效方法。该文对一种条件温和、灵敏度高、选择性好的1-苯基-3-甲基-5-吡唑啉酮(PMP)的衍生化分析方法在糖类化合物的单糖组成、聚合度、取代度、异构体分析以及在N/O-糖链的释放和定量分析等方面的应用进展进行了综述。     

高效阴离子交换色谱-积分脉冲安培检测法同时测定黄酒中的单糖和低聚糖及其指纹图谱的构建

建立了黄酒中葡萄糖、果糖、异麦芽糖、异麦芽三糖、麦芽糖、潘糖、麦芽三糖共7种糖类的高效阴离子交换色谱分离-积分脉冲安培检测的方法。以氢氧化钠和醋酸钠为淋洗液进行梯度洗脱,CarboPac^TM10阴离子交换柱进行分离。该方法可在26 min内实现黄酒中7种糖类的定量分析,在0.5~50 mg/L浓度范围内线性关系良好,样品定量限为0.1 g/L,加标回收率为76.5%~108.4%,精密度(RSD)为3.02%~8.23%。将该法用于不同厂家不同批次的绍兴加饭酒中各种糖类含量的检测,基于所得的检测结果,利用中位数法构建了标准指纹图谱,并采用夹角余弦法评价了各个样品与标准指纹图谱之间的相似度。结果初步显示,不同厂家加饭酒之间的相似度差别较大,该法可作为区别不同厂家酒的依据之一。     

蜂蜜含糖量的高效毛细管电泳测定研究

利用自制的毛细管电泳－电化学安培检测装置，以铜电极为工作电极，在氢氧化钠介质中，分别对２种蜂蜜样品中的糖类化合物进行分离检测，结果满意。     

离子色谱-柱切换技术同步测定饮料中的三氯蔗糖、葡萄糖、果糖和蔗糖

建立了一种离子色谱-柱切换-安培检测技术同步测定饮料中三氯蔗糖、葡萄糖、果糖和蔗糖的方法。以CarboPac PA10阴离子交换保护柱和分析柱进行分离,用水和250 mmol/L NaOH梯度淋洗,脉冲安培检测。弱保留糖类在25 mmol/L NaOH流动相淋洗下分离检测,通过柱切换将保护柱切换至分析柱后,同时切换至250 mmol/L NaOH淋洗,三氯蔗糖仅通过较短的保护柱分离,4种糖类能够得到同步检测。4种糖类在0.01~20 mg/L范围内有良好的线性关系和较低的检出限,重复性好,样品测定的回收率分别为90.38%~102.88%（三氯蔗糖）、95.56%~102.75%（葡萄糖）、101.66%~114.33%（果糖）和105.03%~106.49%（蔗糖）。该方法可广泛应用于食品中强保留物质的测定。     

糖的痕量分析——化学衍生-高效液相色谱法

应用高效液相色谱法分离糖类化合物已日见普遍,但痕量糖类的检测问题尚待解决。目前多数采用的示差折光检测器灵敏度低,且不够稳定,有的转而应用化学衍生法提高糖类的检测灵敏度,但手续繁复,反应条件苛刻。Mooper等用丹酰肼(Dns-hydra-zine)与糖类反应生成丹酰糖类衍生物荧光检测的方法,检出限量可达2—5pmol。我们则选用和比较了几种容易得到的化学衍生试剂与糖反应,研究了它们的反应条件和产物的色谱性能,最后确定以3-羟基-2-萘甲酰肼为化学衍生试剂,最小检出量可达10pmol(葡萄糖)。     

超高效液相色谱-串联质谱法测定螺旋藻多糖的单糖组成

建立了同时测定螺旋藻多糖水解产物中鼠李糖、木糖、阿拉伯糖、果糖、甘露糖、葡萄糖、半乳糖、甘露醇、核糖、岩藻糖、葡萄糖醛酸、半乳糖醛酸12种糖类化合物的超高效液相色谱-串联质谱分析方法。螺旋藻样品经超声波辅助提取,用三氟乙酸水解,经Waters Acquity BEH Amide色谱柱(100 mm×2.1 mm,1.7μm)分离,以10mmol/L甲酸铵和10 mmol/L甲酸铵-乙腈为流动相,在电喷雾电离源负离子(ESI-)模式下,用多反应监测(MRM)模式检测。结果表明,12种糖类化合物的定量限为0.005~0.15 mg/kg,线性范围为0.05~5 mg/L。按照样品中每种糖本底含量的50%、100%、150%进行添加,回收率为80.21%~121.6%。应用该方法对螺旋藻样品进行分析,结果发现:大部分样品都能检测到岩藻糖、半乳糖、阿拉伯糖、鼠李糖、葡萄糖、果糖、木糖、核糖,含量在0.3~889.4 mg/g之间。此外,测定的15个样品中岩藻糖、半乳糖、阿拉伯糖、鼠李糖、葡萄糖、果糖、木糖、核糖是共有组分,含量差异较大,但在所有样品中均未检测到甘露醇和甘露糖。该方法的建立可为阐明螺旋藻多糖的结构组成及其活性提供技术支撑及基础数据。     

气相色谱-质谱法测定橡皮擦中五种邻苯二甲酸酯增塑剂含量

本文建立了一种橡皮擦中5种邻苯二甲酸酯增塑剂的气相色谱-质谱检测方法。采用乙酸乙酯加热搅拌的方法提取目标物,选择离子模式检测,外标法定量。优化的前处理和测定条件下,5种目标物的平均回收率为81.18%~117.92%,相对标准偏差在1.14%~5.57%之间。通过该方法对国内市场上8种橡皮擦样品进行检测,结果5种样品检出邻苯二甲酸二(2-乙基)己酯,含量超过0.1%。     

高效阴离子交换色谱-脉冲安培法检测小鼠尿液中的甘露醇、单糖和乳果糖

采用高效阴离子交换色谱-脉冲安培检测法(HPAEC-PAD)建立了小鼠尿液中甘露醇、单糖(包括半乳糖、葡萄糖、甘露糖和果糖)和乳果糖的分析方法。样品经离心沉淀除去蛋白并过分子膜,以CarboPacTM PA1阴离子交换柱为分离柱,采用NaOH梯度淋洗,脉冲安培四电位检测。结果表明,甘露醇、半乳糖、葡萄糖、甘露糖、果糖和乳果糖在0.1～5.0 mg/L内线性良好,线性相关系数r2为0.988～0.999,样品加标回收率为95.5%～104.2%,检出限为0.0013～0.0048 mg/L。此法准确、快速、简便,能同时对6种糖类化合物进行分析,可以跟踪检测整个糖类代谢过程中甘露醇、单糖和乳果糖之间的代谢关系。     

咔唑-9-乙氧基碳酰肼柱前衍生中性糖的高效液相色谱分析

采用一种新型紫外、荧光衍生试剂咔唑-9-乙氧基碳酰肼(EEOC-Hydrazlde)对5种中性糖(乳糖,甘露糖,葡萄糖,鼠李糖和山梨糖)进行柱前衍生,并通过紫外、荧光检测的方法进行高效液相色谱(HPLC)分析。结果表明：反应温度65℃,时间6．5h,醋酸含量为3．5％(V／V)的条件下,衍生产率可达最大。衍生物的激发和发射波长为λex／λem=293／360nm,紫外检测波长254nm。检出限范围15-60fmol。该方法具有检测灵敏度高,衍生化反应简单,适合糖类化合物的分析。     

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.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

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).