加压毛细管电色谱测定葛根中三种异黄酮类化合物

建立了加压毛细管电色谱(pCEC)检测葛根中异黄酮类化合物葛根素、大豆苷、大豆苷元的方法。采用C18毛细管色谱柱,以NaH2PO4缓冲盐水溶液和甲醇为流动相,优化流动相比例、流动相流速、NaH2PO4缓冲盐水溶液浓度和pH、分离电压等色谱条件。结果表明,在流动相为17.5 mmol/L NaH2PO4缓冲盐水溶液(pH 4.0):甲醇=55:45(V/V),分离电压3 kV,流动相流速80μL/min,检测波长250 nm的条件下,葛根素、大豆苷、大豆苷元质量浓度在200～1000μg/mL范围内线性关系良好,相关系数在0.9960～0.9982之间,平均回收率在98.6%～100.9%之间,RSD为3.1%～3.5%之间。该方法已用于葛根中异黄酮类物质的分离检测。     

大豆二羟异黄酮及三羟异黄酮的高效液相色谱分析

1mol/L盐酸水解大豆及豆制品,乙腈提取,高效液相色谱分析了二羟、三羟异黄酮的含量。以甲醇－2mmol/L乙酸铵(体积比55:45,乙酸铵溶液用乙酸调pH至4.380)为流动相,Hypersil BDS C18色谱分析柱,柱温25℃,260nm紫外检测波长进行分析。二羟、三羟异黄酮的1－500μmol/L的范围内,与峰面积有很好的线性关系 (r=0.9999)。它们的检出限为5ng(S/N=3),平均回收率94.46%以上,6次进样的相对标准差（RSD）小于4％。该法灵敏、重复性好、结果准确、分析迅速。检测大豆及豆制品中异黄酮的含量,得到满意的结果。     

高效液相色谱法测定保健食品中的大豆异黄酮

建立了一种测定保健食品中大豆异黄酮的高效液相色谱分析方法,该方法可以使常见的大豆异黄酮6种主要成分大豆甙、黄豆甙、染料木甙、大豆甙元、黄豆黄素、染料木素得以分离和检测。采用乙腈-磷酸水溶液(pH2.8)作流动相,梯度洗脱,Venusil MP-C18色谱柱(150 mm×4.6 mmi.d.,5μm),流速为1.0 mL/min,紫外检测器,检测波长254 nm。结果表明各组分线性关系良好,相关系数R2为0.9991~0.9998,加标回收率在87%~106.9%,相对标准偏差均小于2%。检出限0.25~0.48μg/mL,该方法可同时测定大豆异黄酮的6种成分。     

反相高效液相色谱法测定豆制品中两种异黄酮甙元的含量

建立了反相高效液相色谱测定异黄酮甙元的方法。采用Hypersil BDS C18色谱柱(250×4.6 mm i.d.,5μm),流动相为甲醇(A)、0.5%乙酸水溶液(B),流速为1.0mL/min,柱温为35℃,检测波长为260 nm,进样量为10μL。结果表明:大豆黄素的线性范围为0.0450~0.3150μg,加标回收率为99.05%,相对标准偏差(RSD)为1.31%;染料木黄酮的线性范围为0.0448~0.3136μg,加标回收率为98.82%,RSD为0.50%。方法可用于豆豉及其它大豆制品中异黄酮甙元的测定。     

高效液相色谱法测定化妆品原料中N-乙酰神经氨酸

建立高效液相色谱法测定化妆品原料中N-乙酰神经氨酸含量的方法。以体积分数为50%的乙酸溶液为水解溶剂,样品于80℃水浴中加热30 min,以CAPCELL PAK SCX柱（250 mm×4.6 mm,5μm）为分析柱,流动相为乙腈-0.1%磷酸水溶液（体积比为80∶20）,等度洗脱,流量为1.0 mL/min,柱温为35℃,采用高效液相色谱二极管阵列检测器测定,以色谱峰面积外标法定量。检测波长为205 nm,进样体积为10μL。N-乙酰神经氨酸的色谱峰面积与质量浓度在10.0～500.0μg/ml范围内线性关系良好,相关系数为0.999 9,方法检出限为0.12μg/mL,定量限为0.4μg/mL。样品加标平均回收率为97.7%～98.9%,测定结果的相对标准偏差为0.37%～1.36%(n=6)。该方法样品处理简便、高效,适用于化妆品原料中N-乙酰神经氨酸的含量测定。     

高效液相色谱法测定保健食品中七烯甲萘醌

建立高效液相色谱法测定保健食品中七烯甲萘醌(MK-7)。含油脂类食品先经脂肪酶酶解,再经异丙醇提取,不含油食品直接使用异丙醇超声提取,采用高效液相紫外检测器进行检测。用Intersil ODS–3 C_(18)型色谱柱(4.6 mm×150 mm,5μm),以甲醇–异丙醇(体积比为75∶25)为流动相,流量为1.0 mL/min,检测波长为270 nm,柱温为40℃,进样体积为20μL。MK-7的质量浓度在0.4-20 mg/L的范围内与色谱峰面积具有良好的线性关系,相关系数为0.9998,方法检出限为0.06 mg/L,定量限为0.2 mg/L。含油脂类食品与不含油脂类食品中MK-7平均加标回收率分别为96.2%、103.2%,测定结果的相对标准偏差分别为0.9%、1.0%(n=9)。室温下,MK-7样品溶液在24 h内稳定。该方法操作简单,可用于保健食品中MK-7的含量测定。     

高效液相色谱法测定保健食品和饮料中的阿斯巴甜

建立了保健食品和饮料中的甜味剂阿斯巴甜的高效液相色谱快速测定方法.固体样品用纯水超声提取;饮料样品超声脱气.取适量提取液或饮料样品,经0.45 μm滤膜过滤后,取20 μL进样色谱柱分析.色谱条件:分离柱为C18柱(250mm×4.6 mm i.d.,10μm),柱温35℃,流动相为V(10 mmol/L KH2PO4,pH 3.50):V(乙腈)=80:20,流速1 mL/min,检测波长210 nm.本法线性范围为0～16 μg,最低检出量为0.0024 μg,回收率为92.3%～102%.相对标准差小于1.6%.本法准确度和精密度均能满足保健食品和饮料中阿斯巴甜测定的要求.     

反相高效液相色谱法制备纯化大豆异黄酮糖苷

利用制备高效液相色谱法从大豆总异黄酮提取物中制备出了3种大豆异黄酮糖苷。在Nova-Pak HR C18色谱柱(100 mm×25 mm i.d.,6 μm)上,以甲醇-体积分数为0.1%的乙酸水溶液(体积比为23∶77)为流动相,流速为20 mL/min,采用 等度洗脱方式,制备了3种大豆异黄酮糖苷,经质谱分析,确认它们分别为大豆苷、黄豆苷和染料木苷。高效液相色谱分析 表明,所制备的3种化合物的纯度均达到了99%以上。     

高效液相色谱法检测肉类食品中4种嘌呤碱

建立了肉类食品中嘌呤含量的多组分高效液相色谱分析方法。采用V(三氟乙酸)∶V(甲酸)∶V(水)=5∶5∶1溶液在90℃下水解样品12min,水解液浓缩后过膜,以0.02mol/LKH2PO4(pH=3.8)为流动相进行色谱分离;流速1.0mL/min;柱温30℃;DAD二极管矩阵检测器检测,检测波长254nm;进样量10μL。在0.4～40mg/L的浓度范围内,各嘌呤的响应峰面积与其相应浓度呈良好相关性,r>0.9999,通过水解条件实验证实,90℃下12min能够使样品中嘌呤完全水解为游离态,且不破坏嘌呤物质,相对标准偏差<16.0%。本方法分离度好,能够快速检测肉类食品中4种主要的嘌呤组分。     

高效液相色谱法测定保健食品中大豆异黄酮含量

建立了高效液相色谱法(HPLC)测定保健食品中大豆异黄酮含量的方法,运用二极管阵列检测器(PDA)建立了4种大豆异黄酮D、G、De、Ge的光谱库,测定了D、G、Ge与De响应值之比.采用PDA检测,C18反相柱,以甲醇∶水∶醋酸(HAC)=55∶45∶1(V/V/V)为流动相测定了同一批保健食品美龄营养片中4种大豆异黄酮D、G、De、Ge的含量分别为2.24%、10.82%0、.085%、0.027%,变异系数小于5%,回收率为92.51%～99.30%.该方法快速,精密度及准确度在允许范围内,可作为保健食品中D,G,De,Ge的同时测定方法.     

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%.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

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.