高效液相色谱法测定橘红丸及蜂蜜中糖的含量

采用高效液相色谱法测定橘红丸及蜂蜜中果糖、葡萄糖、蔗糖、麦芽糖的含量,用prevail carbohydrate ES色谱柱,乙腈–水(体积比77∶23)为流动相,蒸发光散射检测器(ELSD)检测。果糖、葡萄糖、蔗糖、麦芽糖分别在0.103 6～1.554 0,0.107 3～1.609 5,0.107 8～1.617 0,0.111 7～1.675 5μg/mL范围内有良好的线性关系,相关系数(r)分别为0.9909,0.9913,0.9999,0.9989;检出限分别为0.0104,0.0107,0.0107,0.0112μg/mL。样品中果糖、葡萄糖、蔗糖、麦芽糖的加标回收率分别为97.3%,96.6%,101.0%,97.2%,测定结果的相对标准偏差分别0.58%,0.36%,0.40%,0.28%(n=5)。实际样品检测结果显示,多批橘红丸和蜂蜜样品中4种糖含量存在明显差异,且有蜂蜜替代现象。该方法可用于橘红丸中蜂蜜辅料的质量考察。     

超高效液相色谱-蒸发光散射检测法测定蜂蜜中12种糖组分

建立了蜂蜜中果糖、葡萄糖、蔗糖、松二糖、麦芽酮糖、麦芽糖、曲二糖、异麦芽糖、吡喃葡糖基蔗糖、松三糖、蜜三糖和麦芽三糖含量的超高效液相色谱－蒸发光散射测定方法。试样经去离子水溶解,乙腈定容,用0.22 μm滤膜过滤后,采用Amide色谱柱分离,蒸发光散射检测器检测,外标法定量。在优化实验条件下,12种糖得到良好分离,线性相关系数为0.997 7～0.999 8,果糖和葡萄糖的检测结果与示差折光检测法无显著性差异,其余10种糖的平均回收率为90.0 %～105 %,相对标准偏差为0.70%～5.8%。该方法灵敏度高,准确度高,重复性好,适用于蜂蜜中多种糖组分的同时定量分析。用于72批不同蜜种蜂蜜样品中糖组分的检测,发现中国主要蜜源蜂蜜中普遍含有松二糖、麦芽酮糖、麦芽糖等糖组分。该方法和检测数据可为蜂蜜品质和质量评价提供重要支撑。     

高效液相色谱法测定浓缩果汁中5种可溶性糖

建立同时测定浓缩果汁中木糖、果糖、葡萄糖、蔗糖和麦芽糖的高效液相色谱–蒸发光散射检测方法(HPLC–ELSD)。样品采用乙腈–水(50∶50)稀释,用酰胺键合色谱柱BEH Amide分离,蒸发光散射检测器检测,在10 min内完成木糖、果糖、葡萄糖、蔗糖、麦芽糖的分离。浓缩果汁中5种可溶性糖的质量浓度在0.1～2.0 mg/m L与色谱峰面积均呈线性关系,相关系数为0.991 0～0.993 1,检出限为0.23%～0.98%,样品加标回收率为88.6%～104.3%,测定结果的相对标准偏差为2.2%～6.3%(n=6)。该方法快速、准确,可作为浓缩果汁中糖含量的质量控制方法。     

高效液相色谱-蒸发光散射法同时测定蜂蜜中果糖、葡萄糖、蔗糖和麦芽糖

<正>蜂蜜是一种营养丰富的天然保健食品,具有一定的药用价值。蜂蜜成分极为复杂,含各种糖类、酸类及矿物质等。其中糖类为主要成分,含量占60%~75%,包括果糖、葡萄糖、蔗糖和麦芽糖等。国家标准GB 14963-2011《食品安全国家标准蜂蜜》[1]中将各种糖含量作为判断蜂蜜产品质量的重要指标。欧盟2001/110/EC指令等其他国家法规也明确规定了进口蜂蜜中果糖、葡萄糖、蔗糖的含量     

红枣中果糖、葡萄糖与蔗糖的高效液相色谱示差检测分析

建立了同时分析鲜红枣中果糖、葡萄糖和蔗糖的高效液相色谱方法.利用鲜红枣样品进行添加回收实验,获得方法对果糖、葡萄糖和蔗糖测定的平均回收率分别为93.5%、91.8%和89.8%,变异系数3.27%、2.34%、5.86%.结果表明:采用高效液相色谱示差分析方法定量检测鲜红枣中果糖、葡萄糖和蔗糖快速、简便.同时得出方法的检出限为:果糖5.73×10-3mg/mL,葡萄糖5.22×10-3mg/mL,蔗糖3.59×10-3mg/mL,测定结果符合食品检测要求.     

高效液相色谱-蒸发光散射法测定葡萄果实的糖分

建立了测定葡萄果实中果糖、葡萄糖、蔗糖含量的高效液相色谱-蒸发光散射检测法(HPLC-ELSD)。采用Prevail carbohydrate ES色谱柱(250×4.6mm,5μm),流动相为乙腈-水(体积比78∶22),流速1mL/min。选择漂移管温度50℃,N2流速1.5L/min。该条件下,果糖、葡萄糖、蔗糖含量在1.0~50.0μg与其峰面积具有良好的线性关系,相关系数均在0.9996以上;果糖、葡萄糖、蔗糖的平均回收率分别为98.17%、98.47%、99.82%,精密度分别为0.71%、0.92%、0.96%,稳定性分别为1.5%、2.7%、1.8%。方法快速、简单、准确,可用于测定葡萄果实的果糖、葡萄糖、蔗糖。     

超高效液相色谱-串联质谱法测定卷烟中果糖、葡萄糖、蔗糖、麦芽糖

建立超高效液相色谱–串联质谱法测定卷烟中果糖、葡萄糖、蔗糖、麦芽糖4种水溶性糖的含量。样品用水超声提取,稀释过滤后直接进样,以Acquity BEH Amide色谱柱为分析柱,乙腈和水为流动相,梯度洗脱,采用负离子多反应监测模式分析。果糖和葡萄糖的线性范围为2.5～30μg/mL,蔗糖和麦芽糖的线性范围为0.25～3μg/mL,线性相关系数均大于0.997,方法检出限均为0.03 mg/g。加标样品的平均回收率为93.6%～101.0%,测定结果的相对标准偏差为0.7%～2.9%(n=6)。该方法简便、快速,可用于卷烟样品中果糖、葡萄糖、蔗糖、麦芽糖的测定。     

离子色谱脉冲安培法测定蜂蜜中的葡萄糖、果糖、蔗糖

利用离子色谱脉冲安培检测器对蜂蜜中葡萄糖、果糖、蔗糖的测定方法进行了研究。采用CARBOPAC^TM PAl分离柱和脉冲安培检测器,对淋洗分离条件进行了实验,选择50mmol/L NaOH作淋洗液,可使蜂蜜中的葡萄糖、果糖、蔗糖很好地分离。检出限分别为：葡萄糖2μg/kg,果糖2μg/kg,蔗糖5μg/kg。加标回收率为90％－108％。该方法只需简单的前处理、无基体干扰,分离效果好,测定准确率高,适用于蜂蜜中葡萄糖、果糖、蔗糖的测定。     

气相色谱法同时测定初烤烟叶中的4种水溶性糖

建立了一种用三甲基氯硅烷及六甲基二硅胺烷衍生化,气相色谱-氢火焰离子化检测器同时测定初烤烟叶中4种水溶性糖的检测方法。烟叶样品用50%(V/V)的乙腈溶液振荡提取,无需净化,直接用三甲基氯硅烷及六甲基二硅胺烷衍生化,产物通过微型液-液萃取净化后用气相色谱检测。通过优化前处理条件和讨论基质效应,果糖、葡萄糖、蔗糖和麦芽糖的含量均与其峰面积呈良好的线性关系(相关系数为0.9991～0.9999),添加回收率为98.14%～102.45%,重复性较好(RSD<2.2%),该方法适用于初烤烟叶中果糖、葡萄糖、蔗糖和麦芽糖的同时测定。     

高效液相色谱分析糖、糖酸和葡萄糖酸-δ-内酯

糖和糖酸的混合物,在碘酸钠型树脂中用酸性水溶液淋洗,经过离子交换色谱分离后,葡萄糖、葡萄糖酸、蔗糖、果糖和乳糖分别被示差折光检测器测定其含量,葡萄糖酸-δ-内酯在85℃以上水中完全溶解,并转化为葡萄糖酸而被测定。     

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%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.