Online extraction and determination of octylglucoside by reversed-phase high-performance liquid chromatography with evaporative light-scattering detection

A reversed-phase high-performance liquid chromatography method using evaporative light-scattering detection is developed for the determination of residual octylglucoside (OG) levels after a detergent exchange step for in-process samples of a vaccine antigen. The reversed-phase column not only provides separation of the OG but also functions as an extraction column to remove the vaccine antigen from the sample, thereby eliminating off-line sample manipulations. In addition to column selection, the mobile phase is optimized to enhance extraction and separation. The vaccine antigen is irreversibly bound to the column, allowing nonprotein components to interact with the column for separation and elution. The assay is linear over the range of 0.00050-0.050% OG. Precision tested at 0.0010% and 0.0050% OG is 2.9% and 7.2% relative standard deviation, respectively. The limits of quantitation and detection are determined to be 0.00050 and 0.000125% OG, respectively. Accuracy is determined to be 103 and 98%, based on spike recoveries of 0.0010% and 0.0050% OG, respectively.     

Electrochemical study on the keto-enol tautomerization of p-hydroxyphenylpyruvic acid in aqueous solution

The keto-enol tautomerization of p-hydroxyphenylpyruvic acid (pHPP) in aqueous solutions and the complexation reaction between enolic pHPP and boric acid have been studied by electrochemical techniques including linear sweep voltammetry (LSV), pulse voltammetry, and cyclic voltammetry (CV), combining with UV spectrometry. Electrochemical techniques reveal that in aqueous solution, there are two tautomers of pHPP: enolic form and ketonic form; the former exists mainly in freshly prepared pHPP solution, and the latter exists mainly in equilibrium solution. Both enolic and ketonic pHPP are electroactive. The electrochemical oxidation of enolic pHPP gives rise to two anodic waves, I(a) and II(a), while the electrochemical oxidation of ketonic pHPP only results in the observation of the second wave II(a). The oxidation process I(a) is revealed to be associated with the quasi-reversible, two-electron two-proton oxidation of "C=C"group at the side chain of enolic pHPP, and the oxidation process II(a) is proposed to result from the irreversible oxidation of phenolic hydroxyl group. It is observed that in aqueous solution, enolic pHPP can quickly complex with boric acid to yield enol-borate complex that can also oxidize at a glassy carbon electrode to yield an anodic wave.     

Total Synthesis of Several 8, 8",-Biflavones

8,8"-Biflavonoidsareantw0rtantclass0fbiflavonoids.Asasystematicresearchofthe8,8"-biflav0noids,wehavepreviouslyreportedthestudyonthereactionof2'-hydroxychaloneswithl2-H2SO4-DMSOsystem.'InthispaPer,thesynthesisof5,5",7,7',-tetTameth0xy-8,8"-biflavonela2,4,4",7,7"-tetramethoxy-8,8"-biflavone1b',4',4",,5,5,',7,7"-hexamethoxy-8,8"-biflav0ne1c4and4,4"-dibenZyl0xy-5,5",7,7"-tetramothoxy-8,8"-biflavoneldisreported.ThesyntheticmethodisshownintheSchemebelow.2-Hydroxyacet0phenonescondensedwithsubsti…     

Phase transition in single crystal Cs2Nb4O11

We studied temperature dependence of complex capacitance, impedance, and polarized Raman spectra of single crystal Cs2Nb4O11. First, we observed a sharp lambda-shaped peak at 165 degrees C in the complex capacitance, then found drastic changes in the Raman spectra in the same temperature range. Utilizing the pseudosymmetry search of structure space group, we attributed the observed anomalies to a structural change from the room temperature orthorhombic Pnn2 to another orthorhombic Imm2. We also measured room temperature polarized Raman spectra in different symmetries of normal vibrations and assigned high wavenumber Raman bands to the internal vibrations of NbO6 octahedra and NbO4 tetrahedra.     

六味地黄丸的精细指纹图谱分析及模式识别分类研究

采用高效液相色谱建立了六味地黄丸的指纹图谱,对两个厂家的16批产品进行了测定,并结合中药相似度软件和主成分分析法对全指纹图谱和其精细指纹图谱进行了模式识别研究。结果表明,中药相似度软件能够对不同厂家的产品进行区分但也可能造成误判;在主成分分析法的投影图中,两个厂家的产品明显聚为两类,而且不同批次产品的差异也能够显示出来。     

钇对Ti-1100高温钛合金热稳定性和蠕变行为的影响

量了Ｔｉ１１００和Ｔｉ１１００／０１％Ｙ（质量分数）高温钛合金在６００℃／１００ｈ空气中暴露后的拉伸性能及在６００℃／１５０ＭＰａ／１００ｈ条件下的蠕变性能，利用透射电镜观察了合金室温及蠕变后的组织。结果表明，Ｔｉ１１００合金加入０１％的Ｙ后，由于原始β晶粒得到细化，明显改善了其热稳定性；固溶在基体中的硅原子阻碍位错滑移和攀移，使蠕变中的回复过程难于实现；稀土还抑制α２相的长大，所形成的氧化物也阻碍位错的运动。这些均有利于提高Ｔｉ１１００合金的抗蠕变性能。     

Synthesis of a new class of conformationally rigid phosphino-oxazolines: highly enantioselective ligands for Ir-catalyzed asymmetric hydrogenation

[reaction: see text] A new class of conformationally rigid phosphino-oxazoline ligands were synthesized from readily available enantiopure phenyl glycinol. Ir complexes with these ligands are air-stable and highly enantioselective catalysts for asymmetric hydrogenation of aryl alkenes and alpha,beta-unsaturated esters in up to 99% ee.     

The Mechanism on Cyclization, Debenzylation and Oxidation of 1-[1-（Benzyloxy）-3-methylnaphthalen-4-yloxy]propan-2-one

Mansonone compounds represent a series of naturally occurring o-quinones mainly isolated from the heartwood of Mansonia Altissima1 and Ulmus Glabra2. Mansonone F contained oxaphenalene skeleton which was a relatively novel structure and rarely existed in …     

Comparison of Py*+/dU*- charge transfer state dynamics in 5-(1-pyrenyl)-2'-deoxyuridine nucleoside conjugates with amido-, ethylenyl-, and ethynyl linkers

Femtosecond, picosecond, and nanosecond transient absorbance (TA) and picosecond emission kinetics results are presented for three 5-(1-pyrenyl)-2'-deoxyuridine nucleosides each with a different two-atom linker joining pyrenyl C-1 to uracil C-5. The linkers are respectively -NHCO-, -(CH(2))(2)-, and -C[triple bond]C- for PAdU, PEdU, and PYdU. For all three nucleoside conjugates, most conformers undergo intramolecular charge transfer (CT) from their pyrenyl (1)(pi,pi) excited states to form Py(*+)/dU(*-) CT products in ultrashort times: 相似文献   

牙本质中天冬氨酸消旋化程度的测定——手性毛细管气相色谱法与高效液相色谱法的比较

应用手性毛细管气相色谱法（酸性异丙醇、三氟乙酸酐为衍生试剂）、高效液相色谱法（邻苯二甲醛－Ｎ－乙酰－Ｌ－半胱氨酸为手性衍生试剂）同时测定人类第一磨牙牙本质中天冬氨酸的消旋化程度，结果表明，两者均可有效地用于天冬氨酸对映体的分离测定，但气相色谱检测限（０．２ｐｍｏｌ）低于高效液相色谱（１．０ｐｍｏｌ），而变异系数（７％）、总分析时间（１００ｍｉｎ）均高于高效液相色谱（分别对应为４％，３１ｍｉｎ）。