Chitosan-Based Quartz Crystal Microbalance for Alcohol Sensing

Kuwat Triyana,Ahmad Kusumaatmaja,Aditya Rianjanu,Roto Roto,Riowirawan Riowirawan,Trisna Julian,Shidiq Hidayat,Agustinus Sembiring,Iman Santoso

doi:10.3390/electronics7090181

Abstract

Short-chain alcohols are a group of volatile organic compounds (VOCs) that are often found in workplaces and laboratories, as well as medical, pharmaceutical, and food industries. Real-time monitoring of alcohol vapors is essential because exposure to alcohol vapors with concentrations of 0.15–0.30 mg·L−1 may be harmful to human health. This study aims to improve the detection capabilities of quartz crystal microbalance (QCM)-based sensors for the analysis of alcohol vapors. The active layer of chitosan was immobilized onto the QCM substrate through a self-assembled monolayer of L-cysteine using glutaraldehyde as a cross-linking agent. Before alcohol analysis, the QCM sensing chip was exposed to humidity because water vapor significantly interferes with QCM gas sensing. The prepared QCM sensor chip was tested for the detection of four different alcohols: n-propanol, ethanol, isoamyl alcohol, and n-amyl alcohol. For comparison, a non-alcohol of acetone was also tested. The prepared QCM sensing chip is selective to alcohols because of hydrogen bond formation between the hydroxyl groups of chitosan and the analyte. The highest response was achieved when the QCM sensing chip was exposed to n-amyl alcohol vapor, with a sensitivity of about 4.4 Hz·mg−1·L. Generally, the sensitivity of the QCM sensing chip is dependent on the molecular weight of alcohol. Moreover, the developed QCM sensing chips are stable after 10 days of repeated measurements, with a rapid response time of only 26 s. The QCM sensing chip provides an alternative method to established analytical methods such as gas chromatography for the detection of short-chain alcohol vapors.

Highlights

Detection of volatile organic compounds (VOCs) such as alcohols, ethers, esters, haloalkanes, ammonia, and NO2, has gained the interest of researchers across the globe since a few decades ago for environmental protection, human health, industrial processing, and quality control [1]
This study aims to develop an alcohol vapor detector based on the quartz crystal microbalance (QCM) coated with chitosan polymer attached to the surface through a covalent bond
Results and Discussion electrode was coated with chitosan via a self-assembly monolayer of L-cysteine

Summary

Introduction

Detection of volatile organic compounds (VOCs) such as alcohols, ethers, esters, haloalkanes, ammonia, and NO2 , has gained the interest of researchers across the globe since a few decades ago for environmental protection, human health, industrial processing, and quality control [1]. Gas chromatography, and mass spectrometry are often used to detect alcohol vapors [3]. These standard methods are accurate and reliable, they are not real-time, require expensive instrumentations, and are time-consuming, which make them difficult to apply in different conditions. The development of a low-cost sensing system with high accuracy and sensitivity for the detection of alcohol has drawn significant attention recently

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