Supramolecular optical sensor arrays for on-site analytical devices

Supramolecular optical chemosensors are useful tools in analytical chemistry for the visualization of molecular recognition information. One advantage is that they can be utilized for array systems to detect multiple analytes. However, chemosensor arrays have been evaluated mainly in the solution phase, which limits a wide range of practical applications. Thus, appropriate solid support materials such as polymer gels and papers are required to broaden the scope of the application of chemosensors as on-site analytical tools. In this review, we summarize the actual approaches for the fabrication of solid-state chemosensor arrays combined with powerful data processing techniques and portable digital recorders for real-world applications.     

Chemometric tools improving the determination of anti-inflammatory and antiepileptic drugs in river and wastewater by solid-phase microextraction and liquid chromatography diode array detection

An analytical method for the simultaneous determination of seven non-steroidal anti-inflammatory drugs (naproxen, ketoprofen, diclofenac, piroxicam, indomethacin, sulindac and diflunisal) and the anticonvulsant carbamazepine in river and wastewater is reported. The method involves pre-concentration and clean-up by solid-phase microextraction using polydimethylsiloxane/divinylbenzene fibers, followed by liquid chromatography with diode array detection analysis. Owing to the fact that river water samples did not contain interferences and no sensitivity changes due to sample matrix were observed, external calibration was implemented. Standardization was also applied in order to carry out the prediction step by preparing only two diluted standards that were subjected to the pre-concentration step and a set of standards prepared in solvent. For the analysis of wastewater samples, in contrast, it was necessary to implement standard addition calibration in combination with the multivariate curve resolution-alternating least squares (MCR-ALS) algorithm, which allowed us to overcome matrix effect and exploit the second order advantage. Recoveries ranging from 72% to 125% for all pharmaceuticals proved the accuracy of the proposed method in river water samples. On the other hand, wastewater sample recoveries ranged from 83% to 140% for all pharmaceuticals, showing an acceptable performance – considering this sample contains no modeled interferences.     

Separations using a porous-shell pillar array column on a capillary LC instrument

We investigated the achievable separation performance of a 9-cm-long and 1-mm-wide pillar array channel (volume = 0.6 μL) containing 5 μm diameter Si pillars (spacing 2.5 μm) cladded with a mesoporous silica layer with a thickness of 300 nm, when this channel is directly interfaced to a capillary LC instrument. The chip has a small footprint of only 4 cm × 4 mm and the channel consists of three lanes that are each 3 cm long and that are interconnected using low dispersion turns consisting of a narrow U-turn (10 μm), proceded and preceded by a diverging flow distributor. Measuring the band broadening within a single lane and comparing it to the total channel band broadening, the additional band broadening of the turns can be estimated to be of the order of 0.5 μm around the minimum of the van Deemter curve, and around some 1 μm (nonretained species) and 2 μm (retained species) in the C-term dominated regime. The overall performance (chip + instrument) was evaluated by conducting gradient elution separations of digests of cytochrome c and bovine serum albumin. Peak capacities up to 150 could be demonstrated, nearly completely independent of the flow rate.     

Determination of Phenolic Compounds and the Antioxidant Capacity of Ximenia parviflora Benth. var. parviflora (Olacaceae) Fruit by High-Performance Liquid Chromatography with Diode Array Detection

The total phenolic and flavonoid content, phenolic composition, and in vitro antioxidant capacity of ethanolic extracts of Ximenia parviflora Benth. var. parviflora fruits collected at Zinaparo, Michoacan (in central Mexico) were determined. Fruit extracts present a high scavenging activity of 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis[3-ethylbenzothiazoline-6-sulfonic acid] radicals (71.49?±?0.11% and 85.00?±?1.29% inhibition, respectively). The four phenolic compounds identified in fruit extracts by high-performance liquid chromatography with diode array detection were gallic acid, chlorogenic acid, caffeic acid, and quercetin. X. parviflora fruits may be used as a starting material for the extraction of high value antioxidant phenolic compounds with potential applications in the pharmaceutical and dietary supplement industries.     

一种新型高效液相色谱二极管阵列检测器

研制了一种全封闭光学系统的高效液相色谱二极管阵列检测器。这种全封闭结构可以同时提高灵敏度、光谱分辨率和线性范围 ,对萘的最小检测量在2 30 nm下可达 1× 1 0 -10 g,且线性范围比为 5× 1 0 4。该检测器所采集的连续波长吸光度数据可以形成形象直观的三维谱图 ,以几种芳香类化合物为研究对象 ,验证了该系统的各项性能。     

高效液相色谱法分析生物样品中的敌鼠

 研究用阴离子交换、氰基及硅胶柱固相萃取技术分离提取血、尿、肝及肾中的敌鼠。以香豆素作内标 ,用高效液相色谱 二极管阵列检测器方法进行分离鉴定。色谱条件 :分析柱为HypersilBDSC18(5 μm ,15 0mm× 4 6mmi.d .) ,保护柱为PhenomenexODS(4mm× 3 0mmi.d .) ;流动相 :A为 0 5 %离子对A水溶液 ,B为 0 5 %离子对A甲醇溶液 ,以梯度淋洗程序分离 ;检测波长为 2 86nm。当敌鼠的质量浓度在 1mg/L～ 10 0mg/L范围时 ,其浓度同其峰面积与内标物的峰面积之比有良好的线性关系 (r=0 9999) ,最小检出限量为 5ng(按S/N =3计 )。     

Structure and Dynamics in the Nucleosome Revealed by Solid‐State NMR

Eukaryotic chromatin structure and dynamics play key roles in genomic regulation. In the current study, the secondary structure and intramolecular dynamics of human histone H4 (hH4) in the nucleosome core particle (NCP) and in a nucleosome array are determined by solid‐state NMR (SSNMR). Secondary structure elements are successfully localized in the hH4 in the NCP precipitated with Mg²⁺. In particular, dynamics on nanosecond to microsecond and microsecond to millisecond timescales are elucidated, revealing diverse internal motions in the hH4 protein. Relatively higher flexibility is observed for residues participating in the regulation of chromatin mobility and DNA accessibility. Furthermore, our study reveals that hH4 in the nucleosome array adopts the same structure and show similar internal dynamics as that in the NCP assembly while exhibiting relatively restricted motions in several regions consisting of residues in the N‐terminus, Loop 1, and the α3 helix region.     

分子实验室探针在生化分析中的应用研究进展

分子实验室探针（lab-on-a-molecule probe）是基于分子级别的检测,能够提供空间高密度的感应信号,其主要分为分子逻辑门、分子多模式检测以及兼具2者功能的探针,该探针在多分析物的定性以及竞争分析的定量灵敏检测中发挥了重要的作用。对上述3类探针在生化分析（金属阳离子、无机阴离子、氨基酸、蛋白质、致病菌等）中的应用进行了总结。     

基于双定性原则的高效液相色谱-二极管阵列检测法分析中药组分

双定性是根据样品的保留时间和吸收光谱的特征峰进行复合定性的一种新方法。该文基于自行设计及组装的二极管阵列检测器,构建了一套液相色谱-二极管阵列检测系统。采用该色谱系统分别对6种中药饮片中的非法添加物金胺O和枣仁天麻胶囊中的有效成分五味子醇甲进行了分离及定性研究。结果显示,在蒲黄饮片和枣仁天麻胶囊样品色谱图中均存在与目标检测物保留时间接近的色谱峰,进一步通过吸收光谱的特征峰比对,均排除了目标物存在的可能。应用结果证明,基于保留时间/吸收光谱的双定性原则,可以有效排除样品中杂质的干扰,避免假阳性结果,为中药组分研究提供了参考方法。     

Development and validation of a RP-HPLC method for Roflumilast and its degradation products

Roflumilast is a phosphodiesterase type 4 inhibitor that is administered orally as a long-term, in the clinical treatment of chronic obstructive pulmonary disease and asthma. Launched in 2010 for the European market, it currently does not have an official monograph. Here, a reproducible gradient RP-HPLC method was developed and validated for the separation and determination of Roflumilast in the presence of its six major degradation products. Separation was performed on a C₁₈ analytical column (250?×?4.6?mm, 5?µm) with a mobile phase-A of ACN and a phase-B of ammonium acetate buffer (5?mM, pH 4.2) containing triethylamine (0.5% v/v). The most effective RP-HPLC gradient program was determined to be 0/80, 35/10, 36/80, 40/80 (time in minutes/% mobile phase-B). The flow rate was 1.0?ml/min and the column temperature was 25°C. The success of separation of the degradation products with different chemical characteristics was obtained by extending the time of the gradient, changing the proportion of the mobile phases and increasing the velocity of the flow. Two detectors were evaluated for the identification of degradation products and Roflumilast: a diode-arrary detector and a charged aerosol detector. The inability of the charged aerosol detector to dectect one of the six degradation products indicated that the method developed with RP-HPLC and the diode-array detector was more suitable for Roflumilast analysis. The method was validated according to specificity, linearity, LOD, LOQ, accuracy, precision and robustness.