scholarly journals Polymer–Plasticizer Coatings for BTEX Detection Using Quartz Crystal Microbalance

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5667
Author(s):  
Abhijeet Iyer ◽  
Veselinka Mitevska ◽  
Jonathan Samuelson ◽  
Scott Campbell ◽  
Venkat R. Bhethanabotla
Keyword(s):  
Partition Coefficients ◽  
Infinite Dilution ◽  
Quartz Crystal ◽  
Traditional Approach ◽  
Ternary Mixtures ◽  
Time Curve ◽  
Low Concentrations ◽  
Sensitivity And Selectivity ◽  
Quartz Crystal Microbalances ◽  
The Difference

Sensing films based on polymer–plasticizer coatings have been developed to detect volatile organic compounds (VOCs) in the atmosphere at low concentrations (ppm) using quartz crystal microbalances (QCMs). Of particular interest in this work are the VOCs benzene, ethylbenzene, and toluene which, along with xylene, are collectively referred to as BTEX. The combinations of four glassy polymers with five plasticizers were studied as prospective sensor films for this application, with PEMA-DINCH (5%) and PEMA-DIOA (5%) demonstrating optimal performance. This work shows how the sensitivity and selectivity of a glassy polymer film for BTEX detection can be altered by adding a precise amount and type of plasticizer. To quantify the film saturation dynamics and model the absorption of BTEX analyte molecules into the bulk of the sensing film, a diffusion study was performed in which the frequency–time curve obtained via QCM was correlated with gas-phase analyte composition and the infinite dilution partition coefficients of each constituent. The model was able to quantify the respective concentrations of each analyte from binary and ternary mixtures based on the difference in response time (τ) values using a single polymer–plasticizer film as opposed to the traditional approach of using a sensor array. This work presents a set of polymer–plasticizer coatings that can be used for detecting and quantifying the BTEX in air, and discusses the selection of an optimum film based on τ, infinite dilution partition coefficients, and stability over a period of time.

Liquid crystal porphyrins as chemically sensitive coating materials for chemical sensors

2009 ◽  
Vol 13 (11) ◽  
pp. 1188-1195 ◽  
Author(s):  
Ali Şems Ahsen ◽  
Antoni Segade ◽  
Dolores Velasco ◽  
Zafer Ziya Öztürk
Keyword(s):  
Liquid Crystal ◽  
Partition Coefficients ◽  
Quartz Crystal ◽  
Coating Materials ◽  
Alkyl Chains ◽  
Coated Film ◽  
Volatile Organic ◽  
History Of ◽  
Quartz Crystal Microbalances ◽  
Sensitive Coating

Columnar liquid crystal porphyrin compounds have been deposited onto the gold pads of quartz crystal microbalances (QMBs). The sensitivities of the resulting sensors have been measured with respect to volatile organic compounds (VOCs) and have been found to be of interest for future applications. The results show a strong influence of the length of the side alkyl chains, furthermore the thermal history of the coated film also affects the measured properties. The partition coefficients of the coatings have been calculated from the sensor responses.

scholarly journals Interpretation of Quartz Crystal Microbalance Behavior with Viscous Film Using a Mason Equivalent Circuit

Chemosensors ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 9
Author(s):  
Sawit Na Songkhla ◽  
Takamichi Nakamoto
Keyword(s):  
Frequency Shift ◽  
Equivalent Circuit ◽  
Quartz Crystal ◽  
Single Layer ◽  
Frequency Change ◽  
Sensing Applications ◽  
Sensitivity And Selectivity ◽  
Quartz Crystal Microbalances ◽  
Negative Frequency Shift ◽  
Positive Frequency

In odor sensing based on Quartz Crystal Microbalances (QCMs), the sensing film is crucial for both sensor sensitivity and selectivity. The typical response of the QCM due to sorption is a negative frequency shift. However, in some cases, the sorption causes a positive frequency shift, and then, Sauerbrey’s equation and Kanazawa’s equation cannot be applied to this situation. We model the QCM response with a Mason equivalent circuit. The model approximates a single layer of a uniform viscous coating on the QCM. The simulation of the equation circuit shows the possibility of the positive frequency change when the sorption occurs, which is the situation we find in some of the odor sensing applications. We measured the QCM frequency and resistance using the Vector Network Analyzer (VNWA). The QCMs were coated with glycerol, PEG2000, and PEG20M. To simulate odor exposure, a microdispenser was used to deposit the water. A positive frequency shift was observed in the case of PEG2000, and a negative frequency change was obtained for PEG20M. These results can be explained by the Mason equivalent circuit, with the assumption that when the film is exposed to water, its thickness increases and its viscosity decreases.

Quartz Crystal Microbalances Functionalized with Citric Acid-Doped Polyvinyl Acetate Nanofibers for Ammonia Sensing

2020 ◽  
Vol 3 (6) ◽  
pp. 5687-5697 ◽  
Author(s):  
Roto Roto ◽  
Aditya Rianjanu ◽  
Annisa Rahmawati ◽  
Innas Amaliya Fatyadi ◽  
Nursidik Yulianto ◽  
...  
Keyword(s):  
Citric Acid ◽  
Quartz Crystal ◽  
Polyvinyl Acetate ◽  
Ammonia Sensing ◽  
Quartz Crystal Microbalances

Design of 3D printed holder for quartz crystal microbalances

2021 ◽  
Author(s):  
Diego Scaccabarozzi ◽  
Bortolino Saggin ◽  
Marianna Magni ◽  
Pietro Valnegri ◽  
Marco Giovanni Corti ◽  
...  
Keyword(s):  
Quartz Crystal ◽  
Quartz Crystal Microbalances ◽  
3D Printed

scholarly journals EXPERT RESEARCH OF MICROQUANTITIES NARCOTIC, PSYCHOTROPIC SUBSTANCES AND PRECURSORS

2018 ◽  
Vol 18 ◽  
pp. 332-351
Author(s):  
N. Sh. Khalilova ◽  
N. V. Korableva ◽  
V. A. Vetrova ◽  
M. U. Abdullayeva ◽  
Z. U. Usmonaliyeva
Keyword(s):  
High Performance ◽  
Gas Chromatography Mass Spectrometry ◽  
Criminal Cases ◽  
Psychotropic Substances ◽  
Low Concentrations ◽  
Mass Spectrometric Detector ◽  
Sensitivity And Selectivity ◽  
Examination Methods ◽  
Active Substances ◽  
Narcotic Drugs

While investigating and prosecuting criminal cases related to illegal drug trade, psychotropic substances and precursors, microobjects found at the scene of crime, as well as on items related to a crime and its participants, assume ever greater evidentiary. In expert practice, narcotic drugs and psychotropic substances often appear as research objects, that are rarely individual compounds. At that greatest difficulties arise while research of substances that are multicomponent systems and mixtures containing a large number of impurity and ballast substances, as well as low concentrations of active substances. So it is difficult to identify the substance that served as the basis for developing a methodology for the investigation of microquantities of narcotic drugs, psychotropic substances and precursors. Despite the fact that chromatographic analysis is the most common method for the analysis of narcotic drugs, psychotropic substances and precursors, currently due to high information content, sensitivity and selectivity in the world practice of forensic chemical and medical examination, methods of gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography with mass spectrometric detector (HPLC-MS) become one of the most widely used. The use of the HPLC-MS method is the most optimal while research on narcotic, psychotropic substances and precursors by reducing the time of sample preparation, since there is no need for the stage of reagents evaporation and receipt of derivatives, and also it is appear possible to identify non-volatile substances that cannot be analyzed by GC-MS. As a result of the performed researches a methods for the criminalistic research of microquantities of certain narcotic drugs (heroin, morphine, opium, methamphetamine, cocaine, etc.), psychotropic substances (clonidine, bromazepam, ketazolam, trihexyphenidyl, methaqualone, barbital, etc.), precursors (pseudoephedrine, ephedrine) and a poison such as scopolamine using GC-MS and HPLC-MS.

Functionalized Polymers as Receptors for Detection of Cells

2011 ◽  
Vol 64 (9) ◽  
pp. 1256 ◽  
Author(s):  
Miroslava Polreichova ◽  
Usman Latif ◽  
Franz L. Dickert
Keyword(s):  
Soft Lithography ◽  
Quartz Crystal ◽  
Coli Strain ◽  
Yeast Cells ◽  
Label Free ◽  
Sensitive Material ◽  
E Coli ◽  
Label Free Detection ◽  
Quartz Crystal Microbalances ◽  
Cell Strains

Mass sensitive sensors were applied for fast and label-free detection of bio-analytes. Robust and miniaturized sensor devices were fabricated by combining bio-mimetic imprinted surfaces with quartz crystal microbalances for the analysis of yeast and bacteria cells. These sensors allow us to differentiate between different growing stages of yeast cells. Moreover, the viability of cells was detected by structuring quartz crystal microbalance electrodes like a grid. Artificial yeast cells were produced to pattern the recognition layer, giving reversible enrichment of the respective bio-analytes. This approach was followed to ensure the reproducibility of the identical sensitive material in each case, because the properties of each cell depend on its growth stage, which varies over time. The strategy was further applied to develop a sensitive system for Escherichia coli. Structuring of these materials by soft lithography allows differentiation between cell strains, e.g. E. coli (strain W & B) with a five-fold selectivity.

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