Please cite this article in press as: M.M. Ayad, I.M. Minisy, Detection and kinetics of methylamine on chitosan film coated quartz crystal microbalance electrode, Prog. Org. Coat. (2016), http://dx.doi.org/10.1016/j.porgcoat.2016.01.012 ARTICLE IN PRESS G Model POC-3863; No. of Pages 5 Progress in Organic Coatings xxx (2016) xxx–xxx Contents lists available at ScienceDirect Progress in Organic Coatings j o ur na l ho me pa ge: www.elsevier.com/locate/porgcoat Detection and kinetics of methylamine on chitosan film coated quartz crystal microbalance electrode Mohamad M. Ayad ∗ , Islam M. Minisy Department of Chemistry, Faculty of Science, University of Tanta, Tanta 31527, Egypt a r t i c l e i n f o Article history: Received 25 August 2015 Received in revised form 22 September 2015 Accepted 18 January 2016 Available online xxx Keywords: Chitosan Quartz crystal microbalance Methylamine Volatile organic compounds Sensor. a b s t r a c t Chitosan (CHS) coated-quartz crystal microbalance (QCM) electrode was utilized as a sensor for the recognition of methylamine. A homogeneous smooth thin film of CHS coating on the QCM electrode was prepared by the drop casting of CHS solution. The frequency shifts (f) of the QCM due to the adsorption of methylamine on the CHS film were measured as a function of concentrations. Calibration curve was plotted which shows a linear relationship of f (Hz) versus the methylamine concentrations in the range of 0.5–2.3 mg L -1 . In addition to the linearity (R 2 = 0.994) and short response time, the sensor shows a high sensitivity, reproducibility and fast reversibility. The kinetics of methylamine adsorption onto CHS film were calculated. Based on the dynamic analysis of adsorption, the association constant of methylamine vapor molecules with CHS films was estimated to be 11386.3 M -1 . The diffusion coefficients of various aliphatic amines were calculated and showed that methylamine exhibits the highest diffusion coefficient value compared to dimethylamine and diethylamine. © 2016 Elsevier B.V. All rights reserved. 1. Introduction The chemical modification of the quartz crystal microbalance (QCM) electrode by using macrocycles [1–4], mono- and multi- layers [5–7] and bio-organic molecules [8,9] has been widely utilized in the detection of toxic gases and organic vapors due to its extreme sensitivity and simplicity. In the gas systems, it is reported that simple dispersion forces, hydrogen bonding, hydrophilicity and dipole–dipole interactions between the sensor coatings and the analytes play an important contribution to enhance the signal intensity of the sensor. Appropriate coating materials on QCM sensor surfaces have played a crucial role on determining the sensitivity. The production of layers of polymers can be executed by different coating methods e.g. spin coating, spray coating, and drop casting of solutions [10]. Recently, we have utilized polyaniline (PANI) coating on the QCM electrode as a sensor of the pH [11], phosphoric acid [12], chlori- nated hydrocarbons, aliphatic amines and alcohols vapor [13–15]. These sensors showed an excellent reproducibility and reversibil- ity. It has been concluded that the hydrophilicity in addition to dispersion forces, hydrogen bonding or dipole–dipole interactions ∗ Corresponding author. Tel.: +20 40 3404398 ; fax: +20 40 3350804. E-mail address: mohamed.ayad@science.tanta.edu.eg (M.M. Ayad). plays an important contribution to enhance the signal intensity of these sensors. Chitosan (CHS), the organic polymer, bears two types of reac- tive groups, the free amino groups and the hydroxyl groups. CHS is soluble in acidic aqueous solutions and forms strong films from the solution containing as little as 1 wt% of acetic acid. Further- more, CHS has many interesting characteristics including good mechanical strength, and low cost [16,17]. These properties were considered so CHS is utilized to coat the QCM electrode to be used as a gas sensor. Recently, CHS film sensor fabricated by an electro- chemical deposition technique was used to estimate the acetone concentrations in human’s breath, to accurately diagnose diabetes mellitus in patients. The detection was based on the electrical properties of CHS film in the presence of water molecules. Ace- tone normal vapor concentration in the breath varies from 0.3 to 0.9 ppm at room temperature. This sensor highly performed with a good response, recovery, stability and repeatability [18]. Iron oxide gas sensor was fabricated by coating Fe 3 O 4 nanoparticles by CHS. [19] The Fe 3 O 4 /CHS nanocomposite based sensor had a significantly better gas sensing response toward H 2 , CO, C 2 H 5 OH, and NH 3 gases compared to the pristine Fe 3 O 4 based sensor [19]. The same nanocomposite film which was deposited onto indium- tin-oxide (ITO) was utilized for the detection of urea with a good sensitivity [20]. Furthermore, the dispersion of carbon nanopar- ticles into CHS matrix has been used to build up water, toluene and methanol vapors sensor. The sensor shows ranking vapors http://dx.doi.org/10.1016/j.porgcoat.2016.01.012 0300-9440/© 2016 Elsevier B.V. All rights reserved.