A study on the discrimination of xylene isomers vapors by quartz crystal microbalance sensors
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ORIGINAL PAPER
A study on the discrimination of xylene isomers vapors by quartz crystal microbalance sensors Siamak Hashemipour1 · Mohammad Reza Yaftian1 · Hamideh Kalhor1 · Manoochehr Ghanbari1 Received: 25 January 2020 / Accepted: 10 September 2020 © Iranian Chemical Society 2020
Abstract A series of quartz crystal microbalance (QCM) gas sensors were developed for discrimination of the vapor of xylene isomers (ortho-xylene, meta-xylene and para-xylene). The investigated QCM sensors included an Au-bare sensor and those modified by self-assemble monolayer (SAM) formation by 1-butanethiol and 3-methyl-1-butanethiol in the presence of xylene isomers, as reaction solvent. The presence of the investigated thiols made a slight difference on the polarity of the sensors surface, estimated by measuring the contact angles. Although the modified sensors with 1-butanethiol were selective toward orthoxylene vapors as that presented by Au-bare sensor, the sensitivity of the 1-butanethiol-modified sensors was significantly improved with respect to that demonstrated by the unmodified sensor. The sensors modified with 3-methyl-1-butanethiol presented different demeanor for the xylene isomers vapor. This attitude varied with the solvent used through SAM formation process. It was suggested that the observed attitude of the sensors is a reflection of the solvent effect on the structure and decoration of the formed SAM on the sensor surface and the polarity of the sensors’ surface. The results allowed suggesting the fabrication of sensitive sensor arrays for the discrimination of xylene isomers vapors. Keywords Xylene isomers discrimination · Quartz crystal microbalance · Solvent effect · Self-assemble monolayer
Introduction Organic and inorganic environmental pollution monitoring forms the subject of a bulk of recently performed studies with the aim of access to the efficacious methods for controlling their effects on human health and environment [1, 2]. Volatile organic compounds (VOC) such as benzene, toluene and xylenes (abbreviated as BTX compounds) are among the most important air hazardous materials. Individual xylene isomers (ortho-xylene, meta-xylene and para-xylene) and their mixtures are widely used in polyester production, rubber, leather, printing, aerosol paints and lacquers industries [3]. The vapors of xylene isomers menace the human health by impairing the human organs including Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13738-020-02064-0) contains supplementary material, which is available to authorized users. * Mohammad Reza Yaftian [email protected] 1
Department of Chemistry, Faculty of Science, University of Zanjan, 45371‑38791 Zanjan, Iran
the central nervous system, eyes, liver, kidneys, skin and respiratory system [4, 5]. The allowed short-term and longterm limit of xylenes exposure is reported equal to 100 and 50 mg L−1, respectively [4]. Due to the toxicity and health risk of xylenes, the development of fast and effective detection methods fel
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