Evaluation of Antibiotics Residues in Milk and Meat Using Different Analytical MethodsRead the full article
International Journal of Analytical Chemistry publishes research reporting new experimental results and chemical methods, especially in relation to important analytes, difficult matrices, and topical samples.
Chief Editor, Professor Charles L. Wilkins, is a Distinguished Professor of Chemistry and Biochemistry at the University of Arkansas, USA. His research focuses on the development of novel analytical chemistry instrumentation and analysis paradigms.
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Rapid Determination of Three Organic Acids in Polygonum Vivipari Rhizoma via One Marker by HPLC-UV at Equal Absorption Wavelength and Effervescence-Assisted Matrix Solid-Phase Dispersion
A rapid HPLC-UV method for the determination of three organic acids (neochlorogenic acid, chlorogenic acid, and cryptochlorogenic acid) in Polygoni Vivipari Rhizoma (PVR) by one marker was developed. The sample was prepared by effervescence-assisted matrix solid-phase dispersion (EA-MSPD). The separation of compounds was performed on a Poroshell column. The equal absorption wavelength was set as follows: 292 nm (0∼7 min) and 324 nm (7∼10 min). The analytical time including sample extraction and HPLC separation time was 12 min. The analytical method validation such as accuracy (recoveries 99.85%–106.29% and RSD < 2.9%), precision (RSD < 1.3%), reproducibility (RSD < 1.7%), and stability tests (RSD < 0.7% in 24 h) proved that the established HPLC method was suitable for determination of three organic acids in PVR. The contents of three analytes obtained by the external standard method with three markers and the equal absorption wavelength method with one marker were similar (RSD ≤ 2.0%). The developed method, which is rapid and reference compound saving, is an improved quality evaluation method of PVR.
Design and Fabrication of a High Performance Microfluidic Chip for Blood Plasma Separation: Modelling and Prediction of System Behaviour via CFD Method
This paper presents a single-step microfluidic system designed for passive separation of human fresh blood plasma using direct capillary forces. Our microfluidic system is composed of a cylindrical well between upper and lower channel pairs produced by soft photolithography. The microchip was fabricated based on hydrophobicity differences upon suitable cylindrical surfaces using gravitational and capillary forces and lateral migration of plasma and red blood cells. The plasma radiation was applied to attach the polymeric segment (polydimethylsiloxane (PDMS)) to the glass. Meanwhile, Tween 80 was used as a surfactant to increase the hydrophobicity of the lateral channel surfaces. This led to the higher movement of whole blood, including plasma. Fick’s law of diffusion was validated for this diffusion transfer, the Navier–Stokes equation was used for the momentum balance, and the Laplace equation was utilized for the dynamics of the mesh. A model with high accuracy using the COMSOL Multiphysics software was created to predict the capillary forces and chip model validation. RBCs (red blood cells) were measured by the H3 cell counter instrument, by which 99% plasma purity was achieved. Practically, 58.3% of the plasma was separated from the blood within 12 min. Correlation between plasma separation results obtained from software and experimental data showed a coefficient of determination equal to 0.9732. This simple, rapid, stable, and reliable microchip can be considered as a promising candidate for providing plasma in point-of-care diagnostics.
Green Spectrophotometric Determination of Organophosphate in Selected Fruits and Vegetables
A simple, sensitive, precise, and environmentally safe spectrophotometry method was developed and validated for the determination of organophosphate in various fruits and vegetables using a UV-Visible spectrophotometer using a magnesia mixture. The volume of reagent used for analysis and the stability of the color complex were also optimized. The drug showed a stable white color complex at 420 nm. The greenness of the methods was estimated using an ecoscale (84), the Green Analytical Procedure Index, and AGREE (0.89), which were found to be excellent green method based on spectrophotometric determination. The method was validated using ICH guidelines and has acceptable values for linearity (0.5–2.5 mg/ml), accuracy (98.5–102.5%), precision, robustness, limit of detection (0.16 mg), and limit of quantification (0.486 mg). The concentration of the organophosphate in the analyzed sample was in the range of 0.003 to 2.45 mg. Altogether, the proposed green analytical method was found to be a simple, selective, sensitive, accurate, and ecofriendly method for the analysis of organophosphate in various fruits and vegetables.
Discrimination of Traditional Chinese Medicine Syndromes in Type 2 Diabetic Patients Based on Metabolomics-Proteomics Profiles
Aims of the Study. Traditional Chinese medicine (TCM) has thousand years of history, and syndrome differentiation is the foundation and essence of the TCM theory. As it has distinctive advantages in diagnosing and treating the type 2 diabetes mellitus (T2DM), the purpose of this research is to distinguish T2DM patients with or without damp-heat syndrome (DHS), as well as to discover biomarkers associated with syndrome employing the metabolomics-proteomics technique. Materials and Methods. The metabolomics-proteomics of sixty patients with T2DM were acquired by high-performance liquid chromatography (HPLC). In addition, some clinical features, containing total cholesterol (TC), triglycerides (TG), hemoglobin A1c (HbA1c), body mass index (BMI), and low-density lipoprotein (LDL) together with high-density lipoprotein (HDL), were determined via clinical detection strategies. Abundant metabolites and proteins, respectively, were identified with the analysis of liquid chromatography tandem mass spectrometry (LC-MS/MS). Results. 22 differentially abundant metabolites and 15 differentially abundant proteins were determined. The analysis of bioinformatics suggested that the differentially abundant proteins were commonly associated with the renin-angiotensin system, vitamin digestion and absorption, hypertrophic cardiomyopathy, and so on. Furthermore, differentially abundant metabolites were amino acids and were associated with the biosynthesis of CoA and pantothenate, together with the metabolisms of phenylalanine, beta-alanine, proline, and arginine. Combination analysis revealed that the vitamin metabolism pathway was predominantly affected. Conclusions. DHS syndrome can be separated by certain metabolic-proteomic differences, and metabolism is particularly prominent, especially in vitamin digestion and absorption. From the molecular level, we provide preliminary data for the extensive application of TCM in the study of T2DM, and at the same time benefited in a sense diagnosis and treatment of T2DM.
A SiO2 Hybrid Enzyme-Based Biosensor with Enhanced Electrochemical Stability for Accuracy Detection of Glucose
A novel enzyme-based biosensor for glucose detection is successfully developed using layer-by-layer assembly technology. The introduction of commercially available SiO2 was found to be a facile way to improve overall electrochemical stability. After 30 CV cycles, the proposed biosensor could retain 95% of its original current. The biosensor presents good detection stability and reproducibility with the detection concentration range of 1.96 × 10−9 to 7.24 × 10−7 M. This study demonstrated that the hybridization of cheap inorganic nanoparticles was a useful method in preparing high-performance biosensors with a much lower cost.
Bioassay and RP-HPLC Method Development for the Analysis of Extracts and Herbal Products Containing Anthocleista nobilis
Anthocleista nobilis is a common constituent in numerous conventional medications in West Africa. The stem bark of A. nobilis is known to contain brucine and is used to treat intestinal parasites, stomachaches, gonorrhoea, wounds, etc. The extensive use has led to high market value and adulteration of their herbal products. In this work, the antioxidant properties of extracts of A. nobilis are verified, and a validated RP-HPLC method is used to estimate the brucine content of extracts and products containing A. nobilis. Stem bark extracts from ethyl acetate, 96% v/v ethanol, 70% v/v ethanol, and water of A. nobilis were investigated for phytochemical content using standard methods and their antioxidant activity using DPPH and phosphomolybdenum assays. An RP-HPLC method was developed and validated using brucine as a reference standard. The optimized conditions of the developed RP-HPLC method include a Supelcosil C18 column with dimensions 150 × 4.6 mm and particle size of 3 μm, a mobile phase comprising of MeOH : 0.1% v/v HCOOH (65:35 %v/v ) which was injected at a flow rate of 0.8 mL/min, and an injection volume of 50 μL. The wavelength of detection was 274 nm. The developed method was validated as per ICH guidelines. The common phytochemicals among the various extracts were tannins and alkaloids. All extracts exhibited a reasonable antioxidant activity in the DPPH and phosphomolybdenum assays, with the ethanol extract recording the highest activity of 27.681 μg/mL and 696.7452 μg/g AAE, respectively. The content of brucine in the extracts was determined to be 0.0177–0.1259 × 10–3% w/v, whereas the herbal products tested had a content of 0.8950−2.5013 × 10–3% w/v. These levels were below the toxicity threshold of brucine. The developed method could be used for the routine quality control of A. nobilis extracts and formulations.