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A three-dimensional and highly porous polypyrrole (PPy) film was successfully coated onto a copper interdigital electrode (Cu-IDE) surface by electrospinning of soluble PPy nanoparticles.The chemical composition of PPy nanoparticles was analyzed using X-ray photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FT-IR). The Brunauer-Emmett-Teller (BET) analysis confirmed the porous nature of PPy nanoparticles. The field emission scanning electron microscopy (FE-SEM) images of polymer coated Cu-IDE revealed that PPy nanoparticles were assembled by electrical forces to form an outstanding honeycomb-like architecture. As a proof-of-concept demonstration of the functional properties of the electrospun PPy (Es-PPy) film, the polymer coated Cu-IDE was investigated as a sensing device for gas sensor.The as-prepared Es-PPy film proved to be a viable aliphatic amines sensing material with large response, low detection limit, fast response and good repeatability at a low operating temperature of 150˚C. Moreover, the sensor demonstrated an extremely high sensitivity and selectivity to nbutylamine. The calibration sensitivity to n-butylamine is up to three orders of magnitude higher than that of other common aliphatic amines. The detection limit and linear range for determination of n-butylamine were 0.42 ppm and 10.54-21.08 ppm, respectively. Es-PPy gas sensor exhibited good repeatability with RSD ≤ 8% at temperature ranges 90-200°C. The response of the Es-PPy sensor to n-butylamine was compared with electrochemically and drop coated sensors and found that it has an extremely higher response. Finally, the Es-PPy gas sensor was successfully applied to real well water sample analysis.

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This paper describes the development of a simple, rapid, and selective method based on headspace solid-phase microextraction (HS-SPME) combined with ion mobility spectrometry (IMS) for the simultaneous determination of histamine (HIS) and tyramine (TYR) in the canned fish samples. The spectra interferences were eliminated by using a new alternate reagent gas and resulted in an increased sensitivity and selectivity of IMS technique. A dodecylbenzenesulfonate-doped polypyrrole coating was used as a fiber for HS-SPME method. The calibration curves were linear in the range of 30-300 ng g −1 (R 2 > 0.994). Limits of detection for HIS and TYR were 3 and 4 ng g −1 , respectively. The proposed method was successfully applied to determine HIS and TYR in different canned fish samples without derivatization steps. Method validation was conducted by comparing our results with those obtained through gas chromatographymass spectrometry method.

One of the serious complications of COVID-19 is acute kidney injury (AKI), leading to a decrease in kidney function and even death. The concentration of ammonia (NH 3 ) in the exhaled breath (EB) of COVID-19 patients suffering from AKI symptoms will be significantly increased. In this work, the detection of breath NH 3 was performed at gold interdigital electrodes modified with a soluble polypyrrole microparticle and silver nanoparticle film (Au-IDEs/S-PPyMPs/AgNPs) as a noninvasive chemiresistor gas sensor. The response behavior of unmodified and modified gas sensors toward NH 3 and other interfering compounds was studied. The Au-IDEs/S-PPyMPs/AgNPs exhibited NH 3 detection in the linear dynamic range of 1.00−19.23 ppm, with a limit of detection of 0.12 ppm. Finally, the fabricated gas sensor was used to monitor the NH 3 concentration in the EB of COVID-19 patients suffering from AKI symptoms. For this purpose, the gas sensor was validated in 19 EB samples (seven COVID-19−positive patients, four COVID-19−negative patients, and eight post−COVID-19 patients). The gas sensor was directly exposed to the EB samples, followed by recording the changes in electrical resistance via a low-cost digital multimeter. The sensing mechanism was explained as the interaction between breath NH 3 and sensing materials. The breath NH 3 concentrations have a desirable correlation (R 2 = 0.8463) with the estimated glomerular filtration rate (eGFR) values in COVID-19−positive patients. The fabricated gas sensor can distinguish COVID-19−positive patients suffering from AKI symptoms from COVID-19−negative patients and post−COVID-19 patients. The present work can pave the way for the development of a simple and efficient analytical approach for COVID-19 patients with AKI without the need for sample pretreatment.