Time filter

Source Type

Zhang X.,Zhejiang Sci-Tech University | Zhou X.,Focused Photonics Hangzhou Inc | Liu X.,Hunan University | Li X.,Zhejiang Sci-Tech University | Whang W.,Chung - Ang University
Journal of Chromatographic Science | Year: 2016

Acanthopanax species are used in traditional medicine to treat numerous diseases. A simultaneous high-performance liquid chromatography (HPLC) method was developed and validated for the determination of the flavonoid and phenolic content of Acanthopanax leaves. HPLC analysis was performed on an AKZO NOBEL Kromasil 100-5C18 column (250 × 4.6 mm, 5 μm) using a gradient elution of acetonitrile-water containing 0.2% formic acid with a flow rate of 1.0 mL/min, monitored at 320 nm. The method was linear over the range 1-500 μg/mL (determination coefficients R2 > 0.999). Satisfactory intraday and interday precision was achieved, with the relative standard deviation (RSD) <2.99%. The mean recoveries measured at the three concentrations were in the range of 90.11-104.83%, with RSD <2.91% for the targets. Twenty-four samples of Acanthopanax leaves from different species and locations were examined using this analytical method, and their chemical profiles provided information for the chemotaxonomic investigation. The established method is simple, rapid and reliable for the quality control of Acanthopanax leaves of various species from different collections. The complete phenolic and flavonoid profiles of Acanthopanax leaves of various species have been established. © 2015 The Author 2015. Published by Oxford University Press. All rights reserved.

Chen M.-L.,Wuhan University | Li L.-M.,Wuhan University | Yuan B.-F.,Wuhan University | Ma Q.,Focused Photonics Hangzhou Inc | Feng Y.-Q.,Wuhan University
Journal of Chromatography A | Year: 2012

In current study, poly(methacrylic acid-. co-ethylene glycol dimethacrylate) (MAA-. co-EDMA) monolith was successfully prepared for capillary hydrophilic liquid chromatography (cHILIC). The polymerization was optimized by changing the ratio of MAA to EDMA, the type and amount of porogen. The characterization indicated that " hydrophilic" monolithic column possessed homogeneous column bed, good permeability and narrow pore size distribution. Under HILIC mode, the " hydrophilic" monolith prepared with PEG and DMSO showed stronger hydrophilicity than the " hydrophobic" monolith prepared with dodecanol and toluene. Finally, the " hydrophilic" monolith was applied in the separation of tryptic digests of bovine serum albumin (BSA) with cHILIC-ESI-qTOF-MS system. Our results revealed that 49 peptides were identified with 50% sequence coverage under HILIC mode, which was much better than the peptides identified using particulate-packed commercial column with RPLC-ESI-qTOF-MS system or " hydrophobic" monolith with cHILIC-ESI-qTOF-MS system. Taken together, the " hydrophilic" monolithic column prepared in current study, demonstrated the excellent chromatographic performance on the separation of complex samples, which offers the potential application of the monolith on proteomics study. © 2012 Elsevier B.V.

Liu X.,Hangzhou Dianzi University | Zhang T.,Focused Photonics Hangzhou Inc
ICQR2MSE 2011 - Proceedings of 2011 International Conference on Quality, Reliability, Risk, Maintenance, and Safety Engineering | Year: 2011

Reliability is a systematic work, and it must be embedded in the product development process to improve the inherent reliability, so a suitable reliability work flow is very important. Meanwhile, technical details are crucial to the achievement of reliability work, and multidisciplinary knowledge is generally used to direct or audit the design specifics. Therefore, the reliability work has two characteristics: systematic and technical. On the basis of the waterfall model of product development, a modified reliability work flow was introduced, which was established and embedded in the integrated product development model. In this work flow, we ensure the final achievement by controlling some key steps, such as the input of reliability requirement, system and sub-system level reliability design, key module and device reliability testing, evaluation and auditing, and etc. We guarantee the quality of every steps work by defining and regularizing the role responsibilities and work details, thus improve the overall output of reliability work. In order to enhance its operational characteristic, some work was modified or simplified according to the company situation. For example, we emphasize reliability requirements must have two key characteristics: quantitative and decomposable. After near two years implementation, the defects of new products reduced by 10%, and the customer satisfaction increased form 85% to 90%, which shows that this work flow is suitable to our company. It can be expected reasonably that the reliability work flow will be more effective and robust by further modification and standardization as time goes, and the products reliability level will be more and more higher. © 2011 IEEE.

Luo Y.-B.,Wuhan University | Cheng J.-S.,Tsinghua University | Ma Q.,Wuhan University | Ma Q.,Focused Photonics Hangzhou Inc | And 2 more authors.
Analytical Methods | Year: 2011

Due to the excellent mechanical, thermal and electrical properties, graphene/polymer composite is expected to have a variety of applications in analytical chemistry. In this study, a new poly(ethylene glycol dimethacrylate)/graphene composite was prepared by in situ polymerization. The new composite was used for the first time as the extraction coating of stir rod sorptive extraction for the preconcentration of polycyclic aromatic hydrocarbons (PAHs) from water samples. Because of the high specific surface area and π-π electrostatic stacking properties of graphene, the graphene-polymer composite showed higher extraction efficiencies towards most target PAHs from water samples than the neat polymer. Under the optimal conditions, a method for the determination of PAHs in water samples was proposed based on the combination of stir rod sorptive extraction (SRSE) and gas chromatography-mass spectrometry (GC-MS). The limit of detection (LODs) of the developed method for 16 PAHs ranged from 0.005 to 0.429 ng mL-1, depending on the compound. Good reproducibility of method was obtained as intra- and inter-day precisions, the relative standard deviations (RSDs) were less than 12.5% and 12.6%, respectively. © 2011 The Royal Society of Chemistry.

Ye H.,Focused Photonics Hangzhou Inc | Ye H.,Zhejiang University | Xia A.,Hangzhou Dianzi University | Zhang X.,Focused Photonics Hangzhou Inc | And 2 more authors.
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2012

A portable quality analyzer based on long wave near infrared spectroscopy was developed for quality analysis applications in fieldwork. Compared with other analyzers, the analyzer has many advantages, such as compact structure, light weight, small volume, quick response, portability, simple operation and adaptability to environment change. The features and configuration of the analyzer are described in detail both from hardware and software aspects. Performance tests reveal that the analyzer performs well. Furthermore, the analyzer has been successfully applied to non-destructive measurement of protein concentrations of wheat and corn in fieldwork; and the prediction model has good transfer effect. The results demonstrate that the analyzer is excellent and suitable for complex environment.

Discover hidden collaborations