Determination of DMMP Using a Polymer Coated QCM Sensor

2012 ◽  
Vol 542-543 ◽  
pp. 959-962 ◽  
Author(s):  
Wei Li ◽  
Xiao Yan Wen ◽  
Shan Mao Li ◽  
Xin Wang ◽  
Ji Zhang Wang ◽  
...  
Keyword(s):  
Detection Limit ◽  
Thin Layer ◽  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Frequency Shifts ◽  
Adsorption And Desorption ◽  
Fluorinated Polymer

A quartz crystal microbalance (QCM) modified with a thin layer of fluorinated polymer was utilized to determine dimethylmethyl phosphonate (DMMP). Determination was based on the frequency shifts due to the adsorption and desorption of the compound at the surface of modified quartz crystal electrode. Fluorosiloxane was utilized onto the surface of the sensor. The frequency shifts were linear against the concentration of DMMP within the concentration range of 30~210mg•m-3. Good selectivity and sensitivity were obtained with the sensor for DMMP. The detection limit was 10.1 mg•m-3.

Effect of Current Distribution on Quartz Crystal Microbalance Measurements

1997 ◽  
Vol 502 ◽  
Author(s):  
James J. Kelly ◽  
Christopher J. Durning ◽  
Alan C. West
Keyword(s):  
Quartz Crystal Microbalance ◽  
Current Distribution ◽  
Quartz Crystal ◽  
Electrochemical Quartz Crystal Microbalance ◽  
Sensitivity Factor ◽  
A Posteriori ◽  
Frequency Shifts ◽  
Point To Point ◽  
Measured Mass

ABSTRACTSpatially nonuniform electrodeposition can cause discrepancies between predicted and experimentally measured mass loadings on an electrochemical quartz crystal microbalance (EQCM) since the sensitivity of the quartz crystal varies significantly from point to point. These discrepancies can be significant even if the current distribution is nearly uniform. These effects were examined experimentally by varying the conductivity of the electrolyte and the current density during the electrodeposition of copper on an EQCM, effecting changes in the spatial, deposited-mass distribution in a controlled manner. The resulting frequency shifts are in agreement with results predicted by current distribution simulations, validated a posteriori with profilometry measurements. Our results permit determination of the spatial variation of the quartz crystal sensitivity factor or of the current distribution on the EQCM.

Direct mass determination of hydrogen uptake using a quartz crystal microbalance

2007 ◽  
Vol 91 (11) ◽  
pp. 113507 ◽  
Author(s):  
Ihor Kulchytskyy ◽  
Martin G. Kocanda ◽  
Tao Xu
Keyword(s):  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Hydrogen Uptake ◽  
Mass Determination

scholarly journals Quartz crystal microbalance determination of trace metal ions in solution

2007 ◽  
Vol 599 (2) ◽  
pp. 275-287 ◽  
Author(s):  
Abdunasser M. Etorki ◽  
A. Robert Hillman ◽  
Karl S. Ryder ◽  
Andrew Glidle
Keyword(s):  
Trace Metal ◽  
Metal Ions ◽  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Trace Metal Ions

Comparison of Postcolumn Derivatization-Liquid Chromatography with Thin-Layer Chromatography for Determination of Aflatoxins in Naturally Contaminated Corn

1990 ◽  
Vol 73 (4) ◽  
pp. 579-581 ◽  
Author(s):  
Rodney W Beaver ◽  
David M Wilson ◽  
Mary W Trucksess
Keyword(s):  
Liquid Chromatography ◽  
Detection Limit ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Correlation Coefficient ◽  
Low Levels ◽  
Aflatoxin B2 ◽  
Layer Chromatography ◽  
Postcolumn Derivatization

Abstract Quantitation of aflatoxins by liquid chromatography with postcolumn iodine derlvatization (LC-PCD) and fluorescence detection was compared with quantitation by the AOAC CB method, 968.22. Thirty-seven naturally contaminated corn samples were ground and then divided. One portion was extracted, and the extract was cleaned up and analyzed by thin-layer chromatography according to the CB method. The second portion was extracted and cleaned up In a similar fashion, but quantitation was by the LC-PCD method. For aflatoxin B1, concentrations ranging from 0 to 150 ng/g, results obtained by the 2 methods were fitted to a linear equation with the LC-PCD results as the dependent variable. The correlation coefficient was 0.99, the Intercept was near 0, and the slope was near 1. For aflatoxin B2, the correlation coefficient was 0.97, and the Intercept was near 0. However, the slope of the equation relating LC-PCD concentration to TLC concentration was only 0.5. We believe that this lack of equivalence between the methods for determination of aflatoxin B2 is due to overestlmatlon by the TLC method because the low levels present are near the TLC detection limit for B2.

scholarly journals Determination of surface-induced platelet activation by applying time-dependency dissipation factor versus frequency using quartz crystal microbalance with dissipation

2011 ◽  
Vol 8 (60) ◽  
pp. 988-997 ◽  
Author(s):  
Julien Fatisson ◽  
Sania Mansouri ◽  
Daniel Yacoub ◽  
Yahye Merhi ◽  
Maryam Tabrizian
Keyword(s):  
Platelet Activation ◽  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Dissipation Factor ◽  
Surface Hydrophobicity ◽  
Activation Rate ◽  
Immunofluorescence Labelling ◽  
Activation Rates

Platelet adhesion and activation rates are frequently used to assess the thrombogenicity of biomaterials, which is a crucial step for the development of blood-contacting devices. Until now, electron and confocal microscopes have been used to investigate platelet activation but they failed to characterize this activation quantitatively and in real time. In order to overcome these limitations, quartz crystal microbalance with dissipation (QCM-D) was employed and an explicit time scale introduced in the dissipation versus frequency plots ( Df–t ) provided us with quantitative data at different stages of platelet activation. The QCM-D chips were coated with thrombogenic and non-thrombogenic model proteins to develop the methodology, further extended to investigate polymer thrombogenicity. Electron microscopy and immunofluorescence labelling were used to validate the QCM-D data and confirmed the relevance of Df–t plots to discriminate the activation rate among protein-modified surfaces. The responses showed the predominant role of surface hydrophobicity and roughness towards platelet activation and thereby towards polymer thrombogenicity. Modelling experimental data obtained with QCM-D with a Matlab code allowed us to define the rate at which mass change occurs ( A / B ), to obtain an A / B value for each polymer and correlate this value with polymer thrombogenicity.

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