Developed Method Research Articles

Applying UHPLC-HRAM MS/MS Method to Assess Host Cell Protein Clearance during the Purification Process Development of Therapeutic mAbs.

Host cell proteins (HCPs) are one of the process-related impurities that need to be well characterized and controlled throughout biomanufacturing processes to assure the quality, safety, and efficacy of monoclonal antibodies (mAbs) and other protein-based biopharmaceuticals. Although ELISA remains the gold standard method for quantification of total HCPs, it lacks the specificity and coverage to identify and quantify individual HCPs. As a complementary method to ELISA, the LC-MS/MS method has emerged as a powerful tool to identify and profile individual HCPs during the downstream purification process. In this study, we developed a sensitive, robust, and reproducible analytical flow ultra-high-pressure LC (UHPLC)-high-resolution accurate mass (HRAM) data-dependent MS/MS method for HCP identification and monitoring using an Orbitrap Ascend BioPharma Tribrid mass spectrometer. As a case study, the developed method was applied to an in-house trastuzumab product to assess HCP clearance efficiency of the newly introduced POROS™ Caprylate Mixed-Mode Cation Exchange Chromatography resin (POROS Caprylate mixed-mode resin) by monitoring individual HCP changes between the trastuzumab sample collected from the Protein A pool (purified by Protein A chromatography) and polish pool (purified by Protein A first and then further purified by POROS Caprylate mixed-mode resin). The new method successfully identified the total number of individual HCPs in both samples and quantified the abundance changes in the remaining HCPs in the polish purification sample.

A finite element analysis method for random fiber-aggregate 3D mesoscale concrete based on the crack bridging law

Mesoscale modeling is an emerging analytical method that can be used to study fiber-reinforced concrete. However, fine fibers with micrometer diameters are distributed in millions in a standard specimen, so it is impossible to establish a mesoscale model and further analyze it, which severely limits the investigation of the reinforcement mechanism of fine fibers on concrete. This paper efficiently established a highly applicable mesoscale analytical model for random fiber-polyhedral aggregate concrete in Abaqus software based on a comprehensive examination of the crack bridging law and the supplementation of the fiber spacing theory, combined with the improvement of the algorithms of aggregate generation, fiber arrangement, and the judgment of the fiber-aggregate contact by the secondary development method of Python, as well as the matrix-dual arrangement method. Additionally, basalt fiber concrete and mortar specimens were prepared and tested, and the parameters of the model were calibrated to verify the model's authenticity. The result shows that the method proposed in this paper can accurately and efficiently perform mesoscale concrete analysis with fine fibers. In the peak load stage, the fiber has the strongest alleviation effect (Δ = 0.033) on the matrix damage, 10 times that of the crack initiation stage (Δ = 0.003). With the development of damage, fiber stress increases gradually from the crack initiation stage (0.68 σfu), and the growth rate (41.53 %) is the largest at the peak load stage (σfu), which reveals the complex dynamic bridging effect of fiber on the matrix. This investigation proposes a novel and broad applicability methodology for the finite element analysis of fiber-reinforced aggregate mesoscale concrete.

Innovative Geotechnical Solutions for Sustainable Infrastructure Development

Aim: To examine innovative geotechnical solutions for sustainable infrastructure development. Problem Statement: The advancement in the world urbanization together with high rise in global population has alarmed the need for new infrastructures with additional innovative research to be conducted with already existing assets. Thus, It is important that geotechnical engineering should include basic practices targeting resource-efficient and environment-friendly techniques in order to add to sustainable development. Significance of Study: This technical review critically examines the innovative geotechnical solutions for sustainable infrastructure development. The content presented in this manuscript will be beneficial to professionals in the area of geotechnical engineering. Methodology: Recent relevant published articles in the area of innovative geotechnical solutions for sustainable infrastructure development were consulted. These include journal articles, conference papers, Asian Development Bank articles and unpublished doctoral documents. Discussion: The six main environmental objectives of the Taxonomy Regulation to ensure the contours of an environmentally sustainable infrastructure were stated to include: (1) sustainable protection and use of marine and water resources (2) pollution control and prevention (3) switch to a circular economy (4) mitigation of climate change (5) restoration and protection of ecosystems and biodiversity and (6) adaptation of climate change. The three phase methods for sustainability infrastructure development in geotechnics were critically discussed. An imaginary excavation site in the municipality of Rozzano was referenced as a case study to reveal the application of the proposed methodology to the soil treatment systems. It was noticed that the adoption of an LCA introduces additional deep knowledge and the required quantitative analysis for sizing the assessment. Conclusion: The examined innovative geotechnical solutions were contributory to sustainable infrastructure development.

Pengelolaan Cache pada Aplikasi Pencatatan Penjualan Menggunakan Fuzzy Page Replacement Algorithm

The challenges faced in website development are becoming increasingly diverse, particularly in delivering a responsive website that aligns with user preferences. Progressive Web App (PWA) is an advanced web technology that combines the advantages of mobile applications with the ease of access provided by browsers. With features such as offline access and responsiveness across various devices through the utilization of web caching, PWA can offer a better and more interactive user experience. This study aims to develop a sales recording application based on PWA, optimized using an algorithm with a fuzzy approach, namely the Fuzzy Page Replacement Algorithm (FPRA) in cache management. FPRA is applied to enhance cache efficiency through the clustering of pages based on recency, access frequency, and page reference levels using the Fuzzy C-Means algorithm. The research was conducted with a case study on the sales recording application for a fried chicken business, employing the Rapid Application Development (RAD) method for the design and construction of the application. The results indicate that FPRA successfully reduced page load time significantly, achieving up to 37% faster performance based on the average results of five tested scenarios. The implementation of FPRA in the service worker also increased the average performance score of the application by 15 points, from 56 to 71, as evaluated using the Lighthouse testing tool. Thus, the utilization of caching and the application of FPRA in cache management have been proven to enhance application performance.

Routing Task in Dynamic Fog Computing Network

Relevance. In the context of traffic growth, transition to IMT-2030 networks and Telepresence services, the tasks of efficient management of network and computing resources occupy a special place. Fog computing as the next stage of decomposition of the architecture of multi access edge cloud computing is designed to radically change the models and methods of distributing computing tasks, influencing, among other things, the user-operator interaction models. At the moment, there is a whole layer of scientific problems for revealing the possibilities of fog computing. They can be divided into a number of areas, such as: study of models and methods for implementing services of ultra-reliable and ultra-low latency communications, defined in IMT-2020 networks; study of models and methods for ensuring quality of service, including quality of experience; study of methods for live migration of microservices, as well as groups of typical microservices; study of models and methods for distributing resources of dynamic fog computing while ensuring the stability of fog computing forms (clusters, nebulae); one of the potentially effective areas is research in the field of combining federated learning with dynamic fog computing. This paper solves a routing problem that can be attributed to the direction of infrastructure research in dynamic fog computing.Problem statement: research and develop the effective methods for routes determination in a dynamic fog computing network, including tasks of migrating microservices of telepresence services. Goal of the work: research and development of an effective method for ways determination to migrate microservices in communication networks using fog computing technologies, which could take into account not only the characteristics of connections (edges of the network graph), but also the computing capabilities and limitations of fog computing devices, as well as their features - the dynamics of computing devices. Methods: in order to test the proposed method, the program model was developed in the NS-3 modeling environment. Result. Analysis of the results showed the effectiveness of the proposed method within the framework of the task and various application scenarios. Novelty. A microservice migration method has been developed as a new routing protocol in a dynamic fog computing environment, which differs from the known ones in that this method ensures the interaction of fog computing devices for migrating microservices, while achieving a reduction in energy consumption by fog computing devices by 41% and reducing the share of lost packages on average up to 34%. Practical significance: The developed method can be used to implement fog computing in conditions of mobility of end devices in order to achieve the requirements of promising services of IMT-2030 networks.

Development of a simple HPLC method for the determination of urinary O-aminohippuric acid (OAH) and an establishment of OAH reference interval

Background: O-aminohippuric acid (OAH) is considered a low-abundance urinary fluorescent metabolite with the potential to be an innovative lung cancer biomarker. There is a lack of simple methods for measuring urinary OAH metabolite, and the measurement needs to be normalized by urinary creatinine, which is produced at a constant rate. Thus, the newly developed method must be able to determine urinary creatinine and OAH simultaneously in the same run. Objective: This work aimed to develop and validate a simple high-performance liquid chromatography (HPLC) method for measuring urinary OAH and to establish the reference intervals of OAH in healthy individuals. Materials and methods: We synthesized OAH standard in a simple route and optimized simple HPLC method for simultaneous measurement of creatinine and OAH in a single run. Analysis was performed on a RP-C18 column with a gradient elution system of acetonitrile - ammonium acetate buffer (pH 6.5, 100 mM). After implementing optimal conditions, the procedure was compiled according to the International Council for Harmonisation (ICH) validation parameters. The developed method was used for the establishment of reference intervals of a total of 120 random urine samples of healthy individuals. Results: The linear range of the calibration curve for creatinine and OAH were 1-1000 µg/mL and 0.1-100 µg/mL, respectively. The recoveries ranged for both metabolites were between 91.35 % and 109.12%. The relative standard deviations (RSDs) for the intra-day and inter-day results ranged from 0.11-0.66 % to 0.16-1.73 %, respectively. The limits of detection (LOD) and quantification (LOQ) were 0.258 µg/mL and 0.783 µg/mL for creatinine, while OAH was 0.045 µg/mL and 0.137 µg/mL, respectively. The method was successfully applied to establish reference intervals of OAH in healthy individuals and was defined as 0.420-2.287 mmol/mol creatinine. Conclusion: According to various validated parameters, the proposed method was proven to quantify urinary OAH and creatinine in a single run. It can also be analyzed noninvasively without additional sample processing. Reported herein is the first establishment of OAH reference intervals in healthy individuals, which may benefit the utilization of OAH as a noninvasive biomarker for lung cancer detection in the future.

Model and Methods of Traffic Routing in a Communication Network Using UAVs

Relevance. The development of 5G networks and subsequent generations is accompanied by the development of new services, in particular, virtual, augmented reality services, as well as telepresence, as well as radio access networks. In particular, there is an increase in operating frequencies, which poses additional challenges for organizing a network that can meet the requirements for the quality of traffic service from new services and ensure the availability of communication to users. These problems can be solved by various methods of placing access points, including using UAVs. This approach ensures the efficiency of construction and flexibility of the access network structure, but also requires the use of methods for placing access points in relation to users and other elements of the communication network. Problem statement: development of methods for placing routers in a UAV swarm and selecting traffic routes when organizing an access network, in order to improve the efficiency of the communication network. Purpose of the work: improving the efficiency of building an access network using UAVs through the development of clustering methods and distributing routers in a UAV swarm. Methods. The studies were carried out using the provisions of information theory, mathematical optimization methods, graph theory methods and clustering methods. The numerical results were obtained using the numerical simulation method in Python. Result. The developed model and methods allow for the distribution of network routers (access points) located on UAVs taking into account the quality of service and ensuring the construction of a connected mesh network and its connection with the mobile network, which can be used in both modern and future communication networks. Novelty: a modeling and methodological apparatus has been developed that allows for increasing the efficiency of building wireless access networks using UAVs, in particular, allowing for selecting the placement positions of routers in a UAV swarm and the logical structure of the network. The developed modeling and methodological apparatus solves the problem of traffic routing taking into account the quality of its service. Practical significance: the proposed model and methods can be used to organize service in 5G networks and subsequent generations. In particular, they allow for ensuring the availability of communication and the efficiency of network organization in cases of insufficient coverage, as well as in cases of failure of individual network elements. The ability to unload traffic to a local network allows for improving the quality of traffic service in the operator's network.

Wavelet-based convolutional neural network for non-intrusive load monitoring of next generation shipboard Power Systems

In this study, a non-intrusive load monitoring (NILM) framework is developed for next generation shipboard power systems (SPS) based on a discrete wavelet transform signal processing and a convolutional neural network (CNN). We have applied the developed NILM method to a four-zone medium voltage direct current (MVDC) SPS to evaluate the effectiveness of the proposed method. Each zone of the MVDC SPS consists of multiple components, such as propulsion load, pulsed load, high ramp rate load, cooling load, and hotel load. The current signals from the main generators are the main inputs to the NILM model. The current signals are first processed through a discrete wavelet transform to create a coefficient vector that reflects the status of all the components in each zone. Then, a multi-class classification problem is formulated and solved using a CNN architecture model to monitor the load statuses in real time. The results of case studies show that the developed NILM model in comparison with benchmark methods can (i) accurately monitor the status of all components with a total accuracy of over 98%, (ii) identify unique pulsed loads with a total accuracy of over 99%, and (iii) sustain the functionality of load monitoring under extreme events such as cyber/physical attacks, load uncertainty, and noisy inputs.

Method for Controlling Dispersion in Order to Maintain a Quasi-Soliton Pulse Propagation Mode in High-Speed Fiber-Optic Communications System

Relevance: Every year, there is an increasing need to enhance the bandwidth and range of fiber-optic communication systems. The study of methods to control dispersion is relevant and helps maintain a quasi-soliton regime, which is essential for ensuring high-speed, reliable data transmission. Conducted modeling and calculations make this research practical and applicable. This will enable engineers to accurately predict the system's behavior and optimize its performance before implementing it in real-world networks.Problem statement: Investigation of the processes of maintaining a quasi-soliton regime in fibers with decreasing chromatic dispersion and alternating fibers with different signs of chromatic dispersion, both with and without initial chirping.Goal of the work: The development and analysis of techniques to control dispersion in order to maintain a quasi-soliton mode of light propagation in single-mode optical fibers.Methods: The study of the processes of maintaining a quasi-soliton regime was carried out by mathematical and numerical modeling. To substantiate the methods, theoretical analysis and calculations were carried out and schemes for a quasi-soliton fiber-optic communication system were developed and modeling was carried out.Result: The analysis of the results demonstrated the effectiveness of the proposed method and showed the efficiency and stability of the solutions in conditions that were close to real-world scenarios. Novelty: Models for maintaining a quasi-soliton regime and methods for studying them have been developed. The most effective ways to preserve quasi-soliton pulses over long distances have been analyzed.Practical significance: The developed models and research methods can be applied in the educational process and the development of real fiber-optic communication systems.

Overcoming Challenges in Oligonucleotide Therapeutics Analysis: A Novel Nonion Pair Approach.

Oligonucleotide therapeutics (OT) have emerged as promising drug modality for various intractable diseases. Recently, liquid chromatography-mass spectrometry (LC-MS) has been commonly employed for characterizing and quantifying OT in biological samples. Traditionally, the ion pairing-reverse phase (IP-RP) LC-MS method has been utilized in OT bioanalyses; however, this approach is associated with several limitations, including the memory effect and ion suppression effect of IP reagents. Therefore, this study aimed to develop a new RP-LC-MS method that eliminates the need for IP reagents. Our investigation revealed that ammonium bicarbonate was essential for the successful implementation of this nonIP-RP-LC-MS-based bioanalysis of OT. Moreover, the developed method demonstrated high versatility, accommodating the analysis of various natural or chemically modified oligonucleotides. The sensitivity of the method was further assessed using reconstituted plasma samples (the lower limit of quantification in this experiment was 0.5-1 ng/mL). In summary, the developed nonIP-RP-LC-MS method offers an easy, reliable, and cost-effective approach to the bioanalysis of OT.

Мягкие навыки: концепции, проблемы, исследования

<p style="text-align: justify;"><span lang="EN-US">The work is aimed at clarifying the concept of “soft skills”. The materials of the study of concepts, problems, and research of soft skills in a professional environment are presented. The topic of soft skills is extremely relevant, both Russian and foreign students do not exactly understand what soft skills are, which may be explained by the fact that there is currently no single approach to understanding them. The purpose of studying this problem is to review concepts, problems and research on the topic of soft skills in foreign and national scientific literature. The results obtained make it possible to say that soft skills is a broad concept, and does not include a strictly defined list of qualities or abilities. There is evidence that researchers attribute a different set of abilities to soft skills, while different abilities will be most significant for different professional fields. Separately, such abilities can be distinguished as: communication skills, leadership position, decision-making skills, responsibility, empathy, self-esteem, critical thinking, analytical thinking, emotional intelligence (often assessed as part of soft skills in foreign studies). The most effective methods for developing soft skills include: methods for early development, educational tasks related to information search and analysis, critical thinking development, self-management (including the formulation of action plans), teamwork skills, and the presence of social and humanitarian disciplines (“Philosophy" and "Sociology”), as well as specialized courses such as “Team Building” and “Time Management”. It is also emphasized that the level of soft skills development among teachers is important for fostering soft skills in students.</span></p>

Squaraine-Linked Magnetic Covalent Organic Framework as a Solid-Phase Extraction Absorbent to Determine Trace Phenylpyrazoles.

Phenylpyrazoles are widely used pesticides in the food industry. It is highly desirable to develop efficient pre-treatment and analysis methods to extract and detect phenylpyrazoles in complex food matrices. Herein, the study reports novel squaraine-linked zwitterionic core-shell magnetic covalent organic frameworks (MCOFs), which are found to be excellent pretreatment materials for the detection of trace phenylpyrazoles in samples. By coupling MCOFs to magnetic solid-phase extraction (MSPE) with Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) analysis, the detection of phenylpyrazoles (fipronil, fipronil sulfone, fipronil sulfide, fipronil de-sulfoxide, fipronil desulfinyl, ethiprole, and flufiprole) is achieved and shows good linearity at concentrations of 1-800µg L-1 (R2 ≥ 0.9930). The limit of detection (LOD), limit of quantification (LOQ), and recovery rates are 0.01-0.50µg kg-1, 0.04-1.72µg kg-1, and 70.96-115.32%, respectively. More importantly, this method is successfully applied to determine the phenylpyrazoles in commercial egg, poultry, milk, jujube, cabbage, tea, and rice with a detection rate of ≈0.04%. Therefore, the developed method may contribute to a new strategy for the purification and multi-target extraction of complex food matrices.

Pembuatan Aplikasi Transaksi Pembayaran Makanan dan Minuman UMKM Nyonya Buki Kuningan

Food and beverage payment transaction applications are very important in helping MSMEs improve operational efficiency and service quality. This research aims to develop a web-based payment transaction application for Mrs. Buki Kuningan MSMEs. This application is designed using the Customer Relationship Management (CRM) method and tested with a qualitative approach. This research uses the Design and Development Research method. The stages in the design and development methods used are needs analysis, design, development, testing, and evaluation. The data collection techniques used include in-depth interviews, observations, and documentation. Data obtained from various sources will be analyzed using content analysis techniques, descriptive analysis, trial and evaluation. The test results show that this application can increase efficiency, reduce errors, and provide convenience for users. This application is expected to increase MSME income through improving service quality

Separation of triacylglycerol (TAG) isomers by cyclic ion mobility mass spectrometry

Triacylglycerols (TAGs), a major lipid class in foods and the human body, consist of three fatty acids esterified to a glycerol backbone. They can occur in various isomeric forms, including sn-positional, cis/trans configurational, acyl chain length, double bond positional, and mixed type isomers. Separating isomeric mixtures is of great interest as different isomers can have distinct influence on mechanisms, such as digestibility, oxidative stability, or lipid metabolism. However, TAG isomer separation remains challenging with established analytical methodologies such as liquid-chromatography coupled to mass spectrometry (LC-MS). In this study, we developed a method with cyclic ion mobility mass spectrometry (cIMS-MS) for the separation and identification of all types of TAG isomers. First, the influence of different adducts (Li+, NH4+, Na+, and K+) on the separation was studied. Overall, it was concluded that the sodium adduct is the best choice to efficiently separate all types of TAG isomers. In addition, trends were found in the influence of specific structural features on the drift time order. An order of relative influence (from high to low) was established; (1) degree of unsaturation of the fatty acid(s) on an exterior position (if the total degree of unsaturation(s) is equal in both TAGs), (2) acyl chain length on the exterior positions, (3) cis/trans configuration, and (4) double bond (DB)-position. Finally, various cIMS-MS strategies were developed for the separation of mixtures containing four, five, and six isomers. To conclude, the developed methods can be used for separation of complex mixtures of TAG isomers and have great potential to be expanded to isomers of similar types of lipids such as di- and monoacylglycerols. This study also shows the potential of cIMS-MS to be used for the application on real TAG samples.

Distributed learning for kernel mode–based regression

AbstractWe propose a parametric kernel mode–based regression built on the mode value, which provides robust and efficient estimators for datasets containing outliers or heavy‐tailed distributions. To address the challenges posed by massive datasets, we integrate this regression method with distributed statistical learning techniques, which greatly reduces the required amount of primary memory and simultaneously accommodates heterogeneity in the estimation process. By approximating the local kernel objective function with a least squares format, we are able to preserve compact statistics for each worker machine, facilitating the reconstruction of estimates for the entire dataset with minimal asymptotic approximation error. Additionally, we explore shrinkage estimation through local quadratic approximation, showcasing that the resulting estimator possesses the oracle property through an adaptive LASSO approach. The finite‐sample performance of the developed method is illustrated using simulations and real data analysis.

Detection, isolation and characterization of phage-host complexes using BONCAT and click chemistry.

Phages are viruses that infect prokaryotes and can shape microbial communities by lysis, thus offering applications in various fields. However, challenges exist in sampling, isolation and accurate prediction of the host specificity of phages as well as in the identification of newly replicated virions in response to environmental challenges. A new workflow using biorthogonal non-canonical amino acid tagging (BONCAT) and click chemistry (CC) allowed the combined analysis of phages and their hosts, the identification of newly replicated virions, and the specific tagging of phages with biotin for affinity chromatography. Replication of phage λ in Escherichia coli was selected as a model for workflow development. Specific labeling of phage λ proteins with the non-canonical amino acid 4-azido-L-homoalanine (AHA) during phage development in E. coli was confirmed by LC-MS/MS. Subsequent tagging of AHA with fluorescent dyes via CC allowed the visualization of phages adsorbed to the cell surface by fluorescence microscopy. Flow cytometry enabled the automated detection of these fluorescent phage-host complexes. Alternatively, AHA-labeled phages were tagged with biotin for purification by affinity chromatography. Despite biotinylation the tagged phages could be purified and were infectious after purification. Applying this approach to environmental samples would enable host screening without cultivation. A flexible and powerful workflow for the detection and enrichment of phages and their hosts in pure cultures has been established. The developed method lays the groundwork for future workflows that could enable the isolation of phage-host complexes from diverse complex microbial communities using fluorescence-activated cell sorting or biotin purification. The ability to expand and customize the workflow through the growing range of compounds for CC offers the potential to develop a versatile toolbox in phage research. This work provides a starting point for these further studies by providing a comprehensive standard operating procedure.

Extended B‐spline‐based implicit material point method for saturated porous media

AbstractThe large deformation and fluidization process of a solid–fluid mixture includes significant changes to the temporal scale of the phenomena and the shape and properties of the mixed material. This paper presents an extended B‐spline (EBS)‐based implicit material point method (EBS‐MPM) for the coupled hydromechanical analysis of saturated porous media to enhance the overall versatility of MPM in addressing such diverse phenomena. The proposed method accurately represents phenomena such as high‐speed motion in both the quasi‐static and dynamic states by employing a full formulation of coupled hydromechanical modeling. The weak imposition of boundary conditions based on Nitsche's method allows representing the boundary conditions independent of the relative position of the particles and computational grid. In addition, it enables dynamic changes in the boundary domain based on the deformation. The robustness of this boundary representation is reinforced using EBS basis functions, which prevent the degradation of the condition number of the system matrices regardless of the position of the boundary domain with respect to the computational grid. Furthermore, a stabilization method based on a variational multiscale method (VMS) approach is employed to provide the flexibility in choosing arbitrary basis functions for spatial discretization, facilitating the effective construction of EBS. Numerical examples including comparisons between a full formulation and a simplified formulation are presented to demonstrate the performance of the developed method under various boundary conditions and loading states across different time scales.

Ultra-rapid determination of andrographolide and dehydroandrographolide in Andrographis Herba by solid phase extraction and liquid chromatography with mass spectrometry

AbstractAn ultra-rapid analytical method for determination of andrographolide and dehydroandrographolide in Andrographis Herba (AH) was developed by liquid chromatography with mass spectrometry (LC-MS). The sample was ultrasonically extracted with 10 mL 40% (v/v) methanol, and then purified with a C18 solid phase extraction column. The LC separation was performed on a Poroshell 120 EC-C18 column (30 × 2.1 mm, 2.7 μm) and eluted with 0.5 mmol L−1 ammonium acetate aqueous solution and acetonitrile (65:35) at a flow rate of 0.7 mL min−1, and detected by mass spectrometry (MS). The LC-MS analytical time was less than 1 min. The new developed method presented a good linearity (r > 0.9900), precision and repeatability (RSD < 2.0%). The recoveries for andrographolide and dehydroandrographolide were 93.5% (RSD = 2.2%) and 97.7% (RSD = 2.4%), respectively. The developed method was successfully applied in determination of andrographolide and dehydroandrographolide in seven batches of AH samples, and the contents of analytes in all samples were complied with the relative acceptance criteria in Chinese Pharmacopeia (>0.8%). This new developed LC-MS method is an ultra-rapid assay method for AH, which will help to improve the efficiency and reduce the cost of AH sample test.

The use of an RP-HPLC-UV method for the analysis of oxcarbazepine in the presence of its preservatives; stability studies and application to human plasma samples

AbstractA simple, sensitive, selective, accurate and precise method was developed and fully validated for determination of oxcarbazepine (OXC) in presence of their preservatives and determination of oxcarbazepine (OXC) in human plasma. A reversed phase liquid chromatography (RP-HPLC) with UV detection techniques were applied for separation and quantification of studied drug OXC. Successful separation of the drug from methyl paraben (M.P.), propyl paraben (P.P.) and potassium sorbate (P.ST.) was achieved on a Kromasil C18 column (5 μm particle size, pore size 300 Å, l × I.D. 250 × 4.6 mm). The mobile phase that contain aqueous 0.05M potassium dihydrogen phosphate buffer (pH 7): acetonitrile, (50: 50, %v/v). The method was linear over concentration ranges 5.0–50 μg mL−1 for OXC. Bioanalytical validation of the developed method was carried out according to US-FDA guidelines and revealed a good linear relations over a range of (5.0–50), (0.5–10), (0.05–0.15), and (1.0–10) μg mL−1 for OXC, M.P, P.P, and P.ST, respectively, with a correlation coefficient (R2) of more than 0.999. Limit of detection (LOD) were 1.15, 0.03, 0.01 and 0.04 μg mL−1 for OXC, M.P, P.P, and P.ST, respectively, Intra and inter-day precisions, calculated as percentage relative standard deviation (% RSD), were lower than 2.0%. The developed method can be applied for routine drug analysis, therapeutic drug monitoring and bioequivalence studies through the analysis of plasma samples taken from blood bank.

Efficient and sensitive quantification of polar tobacco volatile organic compounds by a micro thermal-assisted sampling device using reduced graphene oxide coupling with thermal desorption-gas chromatography/mass spectrometry

AbstractIt still remains a great challenge to selectively enrich and sensitively quantify the trace volatile organic compounds (VOCs) in real samples with complex matrix. In this study, an integration method combining a selective enrichment medium of reduced graphene oxide (rGO) with a specially designed micro thermal-assisted purge-and-trap sampling device was developed for efficient enrichment and sensitive quantification of trace tobacco VOCs coupling with thermal desorption (TD)-gas chromatography/mass spectrometry (GC/MS). The prepared rGO has been proved to possess excellent enrichment selectivity and capacity for tobacco polar VOCs with the multi-layer structure, good thermal stability and large specific surface area. The specially designed sampling device was efficient and suitable for enriching and sampling trace polar tobacco VOCs coupling with rGO medium. Under the optimized sampling and analytical conditions, the established analytical method could be actually applied for quantification of typical tobacco polar VOCs with the good recoveries of 72.9–128% and the satisfied RSDs of 1.8–19.9% (n = 3). The results suggested that the developed method was selective, sensitive and reliable for enrichment and quantification of trace tobacco polar VOCs.