Novel reversed-phase high-performance liquid chromatography stationary phase with oligo(ethylene glycol) "click" to silica

Oligo(ethylene glycol) (OEG) covalently bonded silica was prepared by using click chemistry and employed as a stationary phase for reversed-phase high-performance liquid chromatography. The column efficiency and effect of organic modifier content on retention were investigated. The separation selectivity was also studied with phenyl compounds and an actual sample of natural products. The results indicated that the stationary phase possessed good separation efficiency and separation selectivity in RP-HPLC mode. Moreover, the stationary phase showed good complementary separation selectivity to the C18 stationary phase. The OEG stationary phase had "clustering" function for "homologous component" in the separation of natural products.     

Two-dimensional LC-MS analysis of components in Swertia franchetiana Smith

An off-line 2-D-LC approach was developed for the separation and identification of components in extracts of Swertia franchetiana Smith, which is a traditional Chinese medicine. An octadecylsilica column was used for further separation of fractions from a cyano column with UV and MS detection. In this method, a longer column was used in the second dimension to improve the separation ability, and "on-column focusing" was adopted to reduce sample loss and pollution on concentrating the fractions from the first dimension. More than 118 and 575 components were detected in the chloroform and n-butanol extracts by this method, respectively. In contrast, only 20 and 95 peaks were detected by the one-dimensional method. Most of the additionally detected compounds were of low-abundance components. Many compounds can be preliminarily identified according to their UV and mass spectra in the two-dimensional method. The obtained results not only demonstrated the powerful resolution of 2-D-LC, but also led to in-depth comprehension of the UV and mass spectra of complex samples.     

Zirconia layer coated mesoporous silica microspheres as HILIC SPE materials for selective glycopeptide enrichment

Characterization of protein glycosylation requires highly specific methods for the enrichment of glycopeptides because of their sub-stoichiometric glycosylation-site occupancy. The hydrophilic affinity based strategy has attracted more attention, owing to its broad glycan specificity, good reproducibility, and compatibility with mass spectrometric (MS) analysis. Several polar matrices have emerged for hydrophilic interaction chromatography (HILIC) approaches, including sepharose, cellulose, ZIC-HILIC and titania. Here, we present the solid-phase extraction (SPE) utility of zirconia coated mesoporous silica (ZrO(2)/MPS) microspheres for glycopeptide isolation prior to MS analysis. The high specificity of this SPE approach was demonstrated by the enrichment of glycopeptides from the digests of model glycoproteins in HILIC mode. ZrO(2)/MPS microspheres show superior selectivity and glycosylation heterogeneity coverage for glycopeptide enrichment to conventional sepharose. Furthermore, digested mixtures of the phosphoprotein α-casein and IgG were also treated with ZrO(2)/MPS HILIC SPE materials, which exhibited that glycopeptides could be effectively enriched with interference from phosphorylated peptides.     

Analysis of highly polar metabolites in human plasma by ultra-performance hydrophilic interaction liquid chromatography coupled with quadrupole-time of flight mass spectrometry

Highly polar metabolites are abundant in human plasma. Analysis of these compounds by standard reverse-phase chromatography is difficult. Highly polar metabolites were extracted by a two-step method. They were analyzed by ultra-performance hydrophilic interaction chromatography (HILIC) coupled to quadrupole-time of flight mass spectrometer detection technology. The middle and low polar fraction were also analyzed using a standard C18 column. Data were extracted by Markerlynx, and analyzed by multivariate statistical methods to discriminate human plasma samples by sex and age. The results not only showed good classification of samples by sex and age, but also revealed new potential biomarkers not revealed by standard RPLC/MS analysis. This study showed that HILIC is an effective technique to analyze highly polar metabolites for metabonomic studies.     

爆炸载荷下分层梯度泡沫铝夹芯板的失效模式与抗冲击性能

采用弹道冲击摆系统开展了爆炸载荷下分层梯度泡沫铝夹芯板的变形/失效模式和抗冲击性能实验研究,并配合激光位移传感器得到试件后面板中心点的挠度-时程响应曲线。研究了炸药当量和芯层组合方式对夹芯板试件变形/失效模式和抗冲击性能的影响。实验结果表明,泡沫铝夹芯板的变形/失效模式主要表现为面板的非弹性大变形,芯层压缩变形、芯层拉伸断裂以及芯层剪切失效。在研究爆炸冲量范围内,非梯度芯层夹芯板的抗冲击性能明显优越于所有分层梯度芯层夹芯板。对于分层梯度夹芯板试件,爆炸冲量较小时芯层组合形式对分层梯度芯层夹芯板的抗冲击性能的影响不大,而爆炸冲量较大时,最大相对密度芯层靠近前面板组合形式的分层梯度夹芯板试件抗冲击性能较好。研究结果可为泡沫金属夹芯结构的优化设计提供参考。     

Metabonomic Study of Lung Cancer and the Effects of Radiotherapy on Lung Cancer Patients: Analysis of Highly Polar Metabolites by Ultraperformance HILIC Coupled with Q-TOF MS

In this study, plasma samples were collected from 28 health volunteers and 66 lung cancer patients. Ultraperformance HILIC/Q-TOF MS-based metabonomic techniques were employed to compare the highly polar metabolites (HPMs) in the plasma of patients with lung cancer and those in the plasma of healthy volunteers. High separation efficiency and good repeatability of the HILIC/Q-TOF MS method were observed. Partial least squares discriminant analysis (PLS-DA) of the data from both ESI+ and ESI? mode revealed good classifications between the health volunteer and the lung cancer patients. This result showed that the HPMs from lung cancer patients and healthy controls were significantly different. The correct classification rate of models in both ion modes reached 100%, indicating that the metabonomics method established in this study could predict the plasma samples with high accuracy. Besides, we found 19 ions that show a significant difference in levels between lung cancer patients and healthy controls. Finally, we conducted a primary study of the effect of radiotherapy on HPMs in lung cancer patients. Clear differences among the HPMs of patients in different radiotherapy periods and significant changes in levels of the 19 ions after radiotherapy were noted. This demonstrated that radiotherapy influences the metabolism system of patients.     

Study on the retention equation in hydrophilic interaction liquid chromatography

Hydrophilic interaction liquid chromatography (HILIC) is an effective technique for separating polar compounds. But its retention equation has not been studied systematically yet. In this study, an appropriate retention equation was established by using eight nucleosides as model analytes and by comparing four retention models on six different HILIC columns. As a result, retention equation Ink = a + b x InC(B) + cxC(B) could be quantitatively described the retention factors with good accuracy in HILIC mode. Based on this equation, the retention times of eight nucleosides under the conditions by other mobile phase can be predicted on each column. All of the predicted relative errors of retention times were smaller than 5%. The established retention model was also successfully applied to predict retention times of the real Traditional Chinese Medicine-Carthaus tinctorius L. sample.     

Hardy’s Inequalities for the Heisenberg Group

Potential Analysis - This article presents two types of Hardy’s inequalities for the Heisenberg group. The proofs are mainly based on estimates of the Fourier transform for atomic functions...     

五味子提取物高效液相色谱分析方法的优化

针对五味子乙醇提取物的复杂体系,借助于复杂样品分析系统软件(CSASS),根据组分在4次简单线性梯度下42个峰的保留时间,快速准确地计算出各组分的液相色谱保留参数a,c值和峰形参数σ,W1/2。借助这些参数,对五味子色谱的分离情况进行高精度仿真预测。在此基础上,应用移动重叠分辨分离图和谱图仿真技术,发展了计算机辅助的五味子提取物的高效液相色谱全局优化方法。在优化条件下,五味子提取物的高效液相色谱分析可在40 min内完成,且常量成分和部分低含量成分都能够得到较好的分离。所建立的方法已成功地用于五味子中化合物保留时间及峰形的预测,并在此基础上对其色谱分离条件进行优化。