Vapors of volatile organic compounds such as benzene, toluene, and xylene (BTX) may cause health concerns. The sensitive detection of these compounds in air remains challenging. In this study, we reported on modification of the Quartz Crystal Microbalance (QCM) sensing chip using polyvinyl acetate (PVAc) film as active coating for the analysis of BTX vapors. The PVAc film was deposited on the QCM sensing chip surface by a spin coating technique. The morphology of the PVAc films was confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The sensitivities of PVAc based QCM system for benzene, toluene, and xylene analyses were 0.018, 0.041, and 0.081 Hz/ppm, respectively. The high sensitivity of the proposed QCM system for analysis of BTX vapors is believed to be due to the effective interaction between the PVAc film and BTX molecules. The analyte vapor pressure appears to also affect the sensitivity. These data show that the prepared QCM sensor has a low time constant, good reproducibility, and excellent stability. It offers an alternative to the developed methods for detection of BTX and possibly other aromatic hydrocarbons in the air.

We report on a method to enhance the sensing performance of polyacrylonitrile (PAN) nanofiber-based QCM sensor overlaid with chitosan. The PAN nanofibers were deposited on the QCM sensing surface by electrospinning technique followed by overlay with chitosan by a drop-casting method. The Fourier transform infrared (FTIR) spectra confirm that chitosan covers the PAN nanofibers. The SEM images show the average diameter of the produced PAN nanofibers was 236 nm, and it increased to 283 nm after overlay with chitosan. The modified QCM sensor has the sensitivity of 18.7 Hz mg -1 L, which is better than that of PAN nanofiber alone of 4.5 Hz mg -1 L. It is an increase nearly 5 times. The analytical parameters of the limit of detection (LOD), sensitivity, a time constant, and stability improved after the PAN nanofiber sensor was overlaid with chitosan. The amine groups present in chitosan interact effectively with safrole, thus increase the sensing response. The proposed device is robust, inexpensive, and convenient for detecting safrole, and can be used as an alternative to those of classical instrumental methods for the analysis of safrole as a drug precursor. ABSTRAK Kajian ini melaporkan tentang kaedah untuk meningkatkan prestasi pengesanan poliakrilonitril (PAN) berasaskan sensor gentian nano QCM yang disaluti dengan kitosan. PAN nanofiber diendap pada permukaan pengesan QCM oleh teknik putaran elektro diikuti dengan salutan kitosan melalui kaedah drop-pemutus. Spektrum transformasi Fourier inframerah (FTIR) mengesahkan kitosan menutup gentian nano PAN. Imej SEM menunjukkan diameter purata gentian nano PAN yang dihasilkan adalah 236 nm dan ia meningkat kepada 283 nm selepas bertindih dengan kitosan. Sensor QCM terubah suai mempunyai kesensitifan 18.7 L mg -1 Hz, lebih baik daripada gentian nano PAN sahaja iaitu 4.5 Hz mg -1 L. Ini merupakan peningkatan hampir 5 kali ganda. Analisis parameter had pengesanan (LOD), kesensitifan, pemalar masa dan kestabilan bertambah baik selepas sensor gentian nano PAN disaluti dengan kitosan. Golongan amina yang hadir dalam kitosan berinteraksi secara berkesan dengan safrola, sekaligus meningkatkan respons pengesanan. Peranti cadangan ini teguh, murah dan mudah untuk mengesan safrola dan boleh digunakan sebagai alternatif kepada metod instrumen klasik untuk menganalisis safrola sebagai pelopor dadah.