scholarly journals Determination of capsaicin using carbon nanotube based electrochemical biosensors

2016 ◽  
Author(s):  
◽  
Thabani Eugene Mpanza
Keyword(s):  
Electron Transfer ◽  
Thermo Gravimetric Analysis ◽  
Computational Techniques ◽  
Gravimetric Analysis ◽  
Multiwalled Carbon ◽  
Chilli Pepper ◽  
Redox Mechanism ◽  
Docking Simulations ◽  
Analytical Technique

This study involves the development of a sensitive electrochemical biosensor for the determination of capsaicin extracted from chilli pepper fruit, based on a novel signal amplification strategy. The study therefore, seeks to provide a sensitive electro-analytical technique to be used for the determination of capsaicin in food and spicy products. Electrochemical measurements using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) modes were utilized in order to understand the redox mechanism of capsaicin and to test the performance of the developed biosensor supported with computational techniques. In this work two different enzymes, Phenylalanine ammonia lyase (PAL) and Glucose oxidase (GOx) were used for electrode modifications respectively. For this purpose three different types of working electrodes namely: glassy carbon electrode (GCE), platinum electrode (Pt-E) and gold electrode (Au-E) were used and their performances were compared. For the first time, the three electrodes were modified with PAL and GOx enzymes on multiwalled carbon nanotubes used in this study and characterized by attenuated total reflectance infrared spectroscopy, transmittance electron microscopy and thermo-gravimetric analysis supported by computational methods. The comparison of the results obtained from the bare and modified platinum electrodes revealed the sensitivity of the developed biosensor with modified electrode having high sensitivity of 0.1863 µg.L-1 and electron transfer rate constant (ks) of 3.02 s-1. To understand the redox mechanism completely, adsorption and ligand-enzyme docking simulations were carried out. Docking studies revealed that capsaicin formed hydrogen bonds with Glutamates (GLU355, GLU541, GLU586), Arginine (ARG) and other amino acids of the hydrophobic channel of the binding sites which facilitated the redox reaction for detection of capsaicin. These results confirm that the PAL enzyme facilitated the electron transfer from the capsaicin ligand, hence improving the biosensing response. Our results suggest potential applications of this methodology for the determination of capsaicin in the food industry.

The Effect of External Conditions on Ignition Temperature of Thermoplastic Polyurethane Elastomers

2013 ◽  
Vol 838-841 ◽  
pp. 14-17
Author(s):  
Ivana Turekova ◽  
Zuzana Szabova ◽  
Tomas Chrebet ◽  
Jozef Harangozo
Keyword(s):  
Thermal Degradation ◽  
Ignition Temperature ◽  
Thermoplastic Polyurethane ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
Polyurethane Elastomers ◽  
External Conditions ◽  
Thermoplastic Polyurethane Elastomers ◽  
The Impact

The paper reports a study of the impact of moisture and age of pellets, as well as an external condition, on the thermal degradation of the thermoplastic polyurethane elastomers. Because thermoplastic polyurethane elastomers are hydroscopic polymer, moisture will have a significant impact on thermal degradation. For determination of the effect of moisture and age were used the thermo gravimetric analysis, differential scanning calorimeter and ISO STN 871: Plastics. Determination of ignition temperature using a hot-air furnace.

Synthesis and Evaluation Methacrylate-Based Monolithic Materials Mixed with Carbon Nanotubes

2014 ◽  
Vol 900 ◽  
pp. 378-381
Author(s):  
Rui Feng
Keyword(s):  
Mercury Intrusion Porosimetry ◽  
Thermo Gravimetric Analysis ◽  
Reversed Phase ◽  
Gravimetric Analysis ◽  
Reversed Phase Liquid Chromatography ◽  
Hydrophobic Properties ◽  
Thermo Gravimetric ◽  
Mercury Intrusion ◽  
Phase Liquid

An effective approach to synthesize methacrylate-based hybrid monoliths was carried out by photopolymerization and the properties of the obtained monoliths mixed with mult-wall carbon nanotube (MWNT) were studied in this paper. The prepared hybrid materials with MWNT in the range of 0-5% total weight of monomers were characterized by Fourier transform infrared spectra, thermo-gravimetric analysis (TGA), and mercury intrusion porosimetry, respectively. Moreover, their porosities were evaluated by the determination of flow rate for different prepared monolithic capillaries. The results showed that the monoliths with more MWNT (1-5%) possessed larger pore sizes between 1-10 μm. The hybrid monoliths have the potential advantages including stronger hydrophobic properties and less resistance for the application of reversed phase liquid chromatography in the micro-column separation.

Determination of Composition of Cellulose and Lignin Mixtures Using Thermo Gravimetric Analysis (TGA)

2007 ◽  
Author(s):  
Kaushlendra Singh ◽  
Mark Risse ◽  
K. C. Das ◽  
John Worley
Keyword(s):  
Lignin Content ◽  
Preliminary Investigation ◽  
Linear Equations ◽  
Thermo Gravimetric Analysis ◽  
Rate Of Change ◽  
Unit Weight ◽  
Gravimetric Analysis ◽  
Thermo Gravimetric ◽  
Bio Oil

The proportional composition of cellulose, hemicellulose, lignin and minerals in a biomass plays a significant role in the proportion of pyrolysis products (bio-oil, char, and gases). Traditionally, the composition of biomass is chemically determined, which is a time consuming process. This paper presents the results of a preliminary investigation of a method using thermo-gravimetric analysis for predicting the fraction of cellulose and lignin in lignin-cellulose mixtures. The concept is based on a newly developed theory of Pyrolytic Unit Thermographs (PUT). The Pyrolytic Unit Thermograph (PUT) is a thermograph showing rate of change of biomass weight with respect to temperature for a unit weight loss. These PUTs were used as input for two predictive mathematical procedures that minimize noise to predict the fractional composition in unknown lignin-cellulose mixtures. The first model used linear correlations between cellulose/lignin content and peak decomposition rate while the second method used a system of linear equations. Results showed that both models predicted the composition of lignin-cellulose mixture within 7 to 18% of measured value. The promising results of this preliminary study will certainly motivate further refinement of this method through advanced research.

scholarly journals Interactive Studies on Synthetic Nanopolymer decorated with Edible Biopolymer and its Selective Electrochemical determination of L-Tyrosine

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Nathiya Dhananjayan ◽  
Wilson Jeyaraj ◽  
Gurunathan Karuppasamy
Keyword(s):  
Thermo Gravimetric Analysis ◽  
Electrochemical Determination ◽  
Electrochemical Analysis ◽  
Oxidation Potential ◽  
Hydroxyl Groups ◽  
Gravimetric Analysis ◽  
Selective Determination ◽  
Adhesive Surface ◽  
Effective Role

Abstract Herein, an edible biopolymer amine Modified Gum Acacia (MGA), successfully encumbered with Electron Beam irradiated Polypyrrole Nanospheres (EB-PPy NSs), was investigated for the effective role in L-Tyrosine (Tyr) biosensing application. The morphology of EB-PPy NSs decorated MGA (EB-PPy/MGA) hybrid nanobiocomposite has been studied by Scanning electron microscopy and its affirmed interactions were characterized by X-ray diffraction, Raman, FT-IR spectroscopy, UV-Visible spectroscopy, Thermo Gravimetric Analysis and Vibrating Sample Magnetometer. The hybrid nanobiocomposite manifested diamagnetic behavior with reduced saturation magnetization (Ms = 1.412 × 10−4 emu/g) to produce more adhesive surface. Amine chains in EB-PPy NSs and hydroxyl groups of MGA contributed to effective immobilization, thus enabling suitable orientation for Tyr determination. The electrochemical analysis illustrated that the proposed nanobiocomposite based sensor exhibited an excellent electrocatalytic activity toward selective determination of Tyr in the linear range of 0.4 to 600 µM with a lower detection limit of 85 nM, low oxidation potential of 0.72 V and good selectivity. Finally, the reliability of the constructed EB-PPy/MGA for Tyr detection was demonstrated in real samples.

A reference installation based on thermo-gravimetric analysis with mass-spectrometric detection as a part of the state primary standard GET 173

2018 ◽  
Vol 84 (6) ◽  
pp. 63-70 ◽  
Author(s):  
M. Yu. Medvedevskikh ◽  
M. P. Krasheninina ◽  
A. S. Sergeeva ◽  
O. S. Shokhina
Keyword(s):  
Mass Fraction ◽  
Water Mass ◽  
Primary Standard ◽  
Thermo Gravimetric Analysis ◽  
The State ◽  
State Primary Standard ◽  
Gravimetric Analysis ◽  
Thermo Gravimetric ◽  
Reference Installation

The issue of assuring the traceability of the results of water determination in solid and liquid substances and materials is discussed. The stages of development and improvement, as well as composition of the State primary measurement standard of mass fraction and mass (molar) concentration of water in liquid and solid substances and materials (GET 173) are considered. The problems of the limited applicability of GET 173 in case of separation of water with different binding energies and impossibility of conducting qualitative analysis of non-water volatile compounds during heating of substances and materials are revealed. The results regarding upgrading of GET 173 due to incorporation of additional reference installation which implements the methods of thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and mass-spectrometry (MS) are presented. The composition and operating principle of the new reference unit are described. An algorithm for estimating the uncertainty of reproducing a unit mass fraction of water using this reference facility is presented and sources of the uncertainty are identified. The results of the experiment on determination of the lower limit of the reproduction range for a unit water mass fraction are presented. We also present the results of comparisons regarding determination of the water mass fraction in crystalline hydrates obtained using the improved State primary standard and high-precision installations of the metrological and leading sectorial research institutes of the European countries. The results of developing a certified reference material of water mass fraction in sodium molybdate dihydrate (Na2MoO4· 2H2O CRM UNIIM 10911–2017 intended for metrological support of measurement instruments and measurement procedures based on thermo-gravimetric method are presented. Additional possibilities which result from the introduction of a new reference installation into the state primary standard of GET 173 are disclosed: identification and the quantification of non-water volatile components, adjustment of drying regimes both in laboratory and process conditions, determination of water content as one of the main impurities in estimating mass fraction of the main component of high-purity substances.

Preparation Thin Film Nanocomposite Membrane Incorporating PMMA Modified MWNT for Nanofiltration

2013 ◽  
Vol 562-565 ◽  
pp. 882-886 ◽  
Author(s):  
Chang Chao Yu ◽  
Hong Wei Yu ◽  
Yue Xia Chu ◽  
Hui Min Ruan ◽  
Jiang Nan Shen
Keyword(s):  
Thin Film ◽  
Carbon Nanotubes ◽  
Methyl Methacrylate ◽  
Multiwalled Carbon Nanotubes ◽  
Organic Phase ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
Multiwalled Carbon ◽  
Selective Permeability ◽  
Thin Film Nanocomposite

Multiwalled carbon nanotubes (MWNTs) grafted by Poly(methyl methacrylate) (PMMA) can well disperse in organic solutions like toluene，which were synthesized via a microemulsion polymerization of methyl methacrylate (MMA) in the presence of acid-modified multiwalled carbon nanotubes (c-MWNTs). The polyamide thin-film nanocomposite (TFN) membranes with embedded PMMA-MWNTs were prepared using piperazine (PIP) and trimesoyl chloride (TMC) on a polyacrylonitrile (PAN) porous substrate via interfacial polymerization for selective permeability. PMMA-MWNTs’ structure was analyzed by Fourier transform infrared spectrophotometry (FTIR), Raman spectrophotmetry (RAM), Scanning electron microscope (SEM) and thermo gravimetric analysis (TGA). Orthogonal experiment was used to study the effect of PIP concentration, TMC concentration and concentration of PMMA-MWNTs in organic phase. The results showed that the membrane performances is good, Na2SO4 rejection is above 98% and water flux is up to 150% improvement over the TFC membrane as PIP in aqueous phase was 2g/L, TMC and PMMA-MWNTs in organic phase were 4g/L and 0.67g/L, respectively . Demonstrated PMMA-MWNTs in the nanofiltration membrane can improve selective permeability.

Solid Fuels Behavior Revealed by Thermo-Gravimetric Analysis

2014 ◽  
Vol 659 ◽  
pp. 301-306
Author(s):  
Marin Bica ◽  
Marius Sorin Sofronie ◽  
Corina Dana Cernaianu
Keyword(s):  
Thermo Gravimetric Analysis ◽  
Solid Fuels ◽  
Mass Composition ◽  
Gravimetric Analysis ◽  
Plant Debris ◽  
Geological Age ◽  
Group Members ◽  
Combustible Wastes ◽  
Composition Changes

Thermogravimetric analysis is also used for the determination of mass composition changes of solid fuels caused by heating processes, coal, and wood or plant debris. Energy characteristics of coal depends on the age of their formation (geological age) and the transformations undergone by organic matter under the influence of geological chemistry (chemical age). Several classification criteria, excluding other problems that may arise in connection with the extraction, preparation and other use than combustion, several classifications have been proposed enabling the sharing of the multitude of solid fuels in groups so that each group members behave similarly during the combustion procedure. Wood and plant debris, combustible wastes, coal, have a heating value depending on their mass composition.

Narrow Diameter Carbon Nanotubes (CNTs) for Polymer Composite Reinforcement

2006 ◽  
Vol 517 ◽  
pp. 129-134
Author(s):  
Muti Mohamed Norani ◽  
Tan Yee Chech ◽  
Abdul Kadir Masrom
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Polymer Composite ◽  
Thermo Gravimetric Analysis ◽  
Small Diameter ◽  
Ni Catalyst ◽  
Gravimetric Analysis ◽  
Multiwalled Carbon ◽  
Mechanical Reinforcement ◽  
Composite Reinforcement

Strong and versatile carbon nanotubes are finding new applications in improving conventional polymer-based fibers. Nanotube-reinforced composites could ultimately provide the foundation for a new class of strong and lightweight fibers with properties such as electrical and thermal conductivity unavailable in current fibers. A recent research has discovered that the best type of nanotube for polymer composite reinforcement is the small diameter multiwalled nanotubes (MWNTs). Here, a catalytic technique has been developed to produce narrow diameter bulk multiwalled carbon nanotubes of less than 38 nm. Structural characterizations including scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis (TGA) and Raman spectroscopy conducted on CNTs grown on three different catalysts, namely iron, cobalt and nickel have indicated that the catalyst used affects their sizes and crystallinity. Results showed that the smallest CNTs could be obtained by catalytic growth on Ni catalyst. The study has proven that with the skillful use of catalyst, a range of narrow sized nanotubes could be produced, providing the material needed to investigate the optimum diameter for the best mechanical reinforcement of polymer composites.

Synthesis of Smart Mesoporous Materials

2003 ◽  
Vol 775 ◽  
Author(s):  
G.V.Rama Rao ◽  
Qiang Fu ◽  
Linnea K. Ista ◽  
Huifang Xu ◽  
S. Balamurugan ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Mesoporous Materials ◽  
Fluorescent Dyes ◽  
Thermo Gravimetric Analysis ◽  
Molecular Transport ◽  
Solute Diffusion ◽  
Gravimetric Analysis ◽  
Stimuli Responsive ◽  
Porous Network ◽  
Hybrid Mesoporous Materials

AbstractThis study details development of hybrid mesoporous materials in which molecular transport through mesopores can be precisely controlled and reversibly modulated. Mesoporous silica materials formed by surfactant templating were modified by surface initiated atom transfer radical polymerization of poly(N-isopropyl acrylamide) (PNIPAAm) a stimuli responsive polymer (SRP) within the porous network. Thermo gravimetric analysis and FTIR spectroscopy were used to confirm the presence of PNIPAAm on the silica surface. Nitrogen porosimetry, transmission electron microscopy and X-ray diffraction analyses confirmed that polymerization occurred uniformly within the porous network. Uptake and release of fluorescent dyes from the particles was monitored by spectrofluorimetry and scanning laser confocal microscopy. Results suggest that the presence of PNIPAAm, a SRP, in the porous network can be used to modulate the transport of aqueous solutes. At low temperature, (e.g., room temperature) the PNIPAAm is hydrated and extended and inhibits transport of analytes; at higher temperatures (e.g., 50°C) it is hydrophobic and is collapsed within the pore network, thus allowing solute diffusion into or out of the mesoporous silica. The transition form hydrophilic to hydrophobic state on polymer grafted mesoporous membranes was determined by contact angle measurements. This work has implications for the development of materials for the selective control of transport of molecular solutes in a variety of applications.

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