In this study, the ochratoxin A (OTA) interaction with some metal cations exhibits a quenching effect of the Cu2+, Co2+, and Ni2+ in the OTA intrinsic fluorescence intensity. The property of the OTA fluorescence change in complexation with the Cu2+ has been applied in developing a label-free and selective fluorimetric sensor for fast detection of the OTA trace amounts in wheat flour samples. The achieved color difference map (CDM) based on the spectral profile provides the technical support for the rapid visual sensing of OTA in the wheat flour samples. The feasibility of the hybrid fluorimetric sensor and visual OTA detection in wheat flour samples has been confirmed with the high-performance liquid chromatography (HPLC) method as a standa

In this work, we fabricated fast-responsive and highly sensitive chemiresistive sensors based on nanocomposites of polypyrrole and graphitic materials such as graphene oxide (GO), reduced graphene oxide (RGO), and sulfonated graphene (SRGO) by an in situ chemical oxidative polymerization method. The synthesized nanocomposites were characterized using field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD). The effects of the operating temperature of different nanocomposites were investigated at four temperatures (28, 40, 50, and 60 ?C), and the results were compared with that of the polypyrrole-based sensor. The experimental resul

Photoconductive films in near-infrared (NIR) were fabricated based on low bandgap (1.36?eV) polypyrrole (PPy) and polypyrrole doped with cadmium sulfide quantum dots (PPy/CdS QDs) as organic photodetectors (PDs). The performance of the PDs was evaluated when the PPy incorporated with different amounts of CdS QDs during the chemical polymerization. The represented PDs showed good photosensitivity at 850?nm with different light intensities (0.4–173?mW) and their responses were linear dependency with increasing the light intensities. The best photosensitivity behavior was obtained when the PPy doped with 22?ppm of CdS QDs and the photoresponsivity was enhanced almost six times compared to the undoped PPy PD. The PPy/CdS QDs (22?ppm) PD exhib

We report the facile (one-step) in situ doping of soluble conducting polypyrrole (PPy) with cadmium sulfide quantum dots (CdS QDs) aimed at tuning the mid-infrared (MIR) (2.5–25 μm) photoconductivity of PPy films with a planer structure. The doping was done during chemical polymerization of PPy with different mass ratios (0–1800 ppm) of the as-synthesized CdS QDs. The PPy/CdS QD films were fabricated by electrospray coating between gold interdigitated electrodes. The incident light in the MIR region (7.62 mW/cm2) was chopped, the prepared film was illuminated with it, and the photocurrent generated was recorded. Doping with CdS QDs at 2–15 ppm increased the photoconductivity of PPy as they generated greater photocurrent than

This paper describes the development of a simple, rapid, and sensitive method based on headspace solid-phase microextraction (HS-SPME) combined with ion mobility spectrometry (IMS) for the simultaneous determination of antidepressant drugs, sertraline (SER), imipramine (IMI) and alprazolam (ALP), in human plasma samples. IMS equipped with corona discharge (CD) ionization along with HS-SPME has been successfully applied for quantitative analysis without derivatization steps. A dodecylbenzenesulfonate doped polypyrrole coating was used as a fiber for HS-SPME. The effects of various parameters on microextraction efficiency, including extraction temperature, extraction time, ionic strength, salt concentration and pH of the sample, were also eva

A selective detection strategy for salicylic acid (SA) based on the electrosorption/electrodesorption process using an electrochemically controlled solid phase extraction (EC-SPME) configuration is presented. We used conducting polymer polypyrrole (PPy) bearing the anionic dopant nitrate (PPy/nitrate) as a sorbent element for the extraction of SA in plasma and urine samples. The vertically grown nanosheets conducting film was directly synthesized by cyclic voltammetry method on a rod-shaped stainless steel electrode. The prepared electrode was employed for selective electrosorption of SA from sample solutions by applying positive potential and following its successive electrodesorption by the use of negative potential. Several parameters li

Methanol is highly toxic for human, so methanol detection is valuable especially in water and ethanol medium without complicated and time consuming procedure. In this work, we present a new fluorescence probe for direct detection of methanol in aqueous and ethanol medium based on the ZnS:Mn2+ quantum dot (QDs) and soluble N-methylpolypyrrole (NMPPy) hybrid. Moreover, the number of spectroscopic techniques were used to study the chemical composition and optical properties of the resultant QDs as well as investigation on the sensing mechanism toward methanol. Also, methanol can be determined by using ZnS:Mn2+ QDs/NMPPy hybrid based switchable fluorescence sensing system, with high sensitivity, high selectivity and a very good detection limit

A gas-phase study concerning the interaction between macrocyclic ligands and different molecular ion guests (H3O+, NH4+, CH3NH3+) was performed using ion mobility spectrometry and mass spectrometry. 18-crown-6 (18C6), diaza18-crown-6 (DA18C6) and cryptand [222] (C222) ligands were selected for the investigation of structural properties on the nature of complexes formed. Characterization of complexes was performed by ESI-TWIM-TOFMS. In this study, the importance of the type of donating atom in the ring on complex formation was investigated by comparison of the ion mobility spectra of 18C6 and DA18C6 at various temperatures. Different complexation behaviors of ligands showed that the nature of species formed strongly depends on the structural

Methanol is highly toxic for human, so methanol detection is valuable especially in water and ethanol medium without complicated and time consuming procedure. In this work, we present a new fluorescence probe for direct detection of methanol in aqueous and ethanol medium based on the ZnS:Mn2+ quantum dot (QDs) and soluble N-methylpolypyrrole (NMPPy) hybrid. Moreover, the number of spectroscopic techniques were used to study the chemical composition and optical properties of the resultant QDs as well as investigation on the sensing mechanism toward methanol. Also, methanol can be determined by using ZnS:Mn2+ QDs/NMPPy hybrid based switchable fluorescence sensing system, with high sensitivity, high selectivity and a very good detection limit

We report the facile (one-step) in situ doping of soluble conducting polypyrrole (PPy) with cadmium sulfide quantum dots (CdS QDs) aimed at tuning the mid-infrared (MIR) (2.5–25?μm) photoconductivity of PPy films with a planer structure. The doping was done during chemical polymerization of PPy with different mass ratios (0–1800?ppm) of the as-synthesized CdS QDs. The PPy/CdS QDs films were fabricated by electrospray coating between gold interdigitated electrodes. The incident light in the MIR region (7.62?mW/cm2) was chopped, the prepared film was illuminated with it, and the photocurrent generated was recorded. Doping with CdS QDs at 2–15?ppm increased the photoconductivity of PPy as they generated greater photocurrent than the und

This paper describes the development of a simple, rapid, and sensitive method based on headspace solid-phase microextraction (HS-SPME) combined with ion mobility spectrometry (IMS) for the simultaneous determination of antidepressant drugs, sertraline (SER), imipramine (IMI) and alprazolam (ALP), in human plasma samples. IMS equipped with corona discharge (CD) ionization along with HS-SPME has been successfully applied for quantitative analysis without derivatization steps. A dodecylbenzenesulfonate doped polypyrrole coating was used as a fiber for HS-SPME. The effects of various parameters on microextraction efficiency, including extraction temperature, extraction time, ionic strength, salt concentration and pH of the sample, were also eva

Inorganic-organic hybrids are an advanced class of luminescent materials showing great promise for fabrication of highly sensitive and selective optical sensors. In the present study, a novel CdS quantum dots/N-methylpolypyrrole (CdS QDs/NMPPY) hybrid was synthesized via the direct polymerization of NMPPY on L-cysteine capped CdS QD aggregates. A number of characterization techniques including FTIR, DLS, FESEM, UV–vis, and fluorescence spectroscopies were used to study the chemical composition, morphology and optical properties of the resultant QDs/polymer hybrid. The as-synthesized CdS QDs/NMPPY hybrid shows a bright emission at 459 nm under excitation at 367 nm in water. Also the results show the role of sodium dodecyl benzenesulfon

A new polypyrrole-bromophenol blue (PPy-BPB) compound was synthesized in nanosphere and nanorod forms on quartz crystal microbalance (QCM) gold electrode by direct one-step electrochemical deposition, and utilized for highly sensitive determination of nitroexplosive compounds’ vapors in the ambient temperature in open air and through a home-made vapor generation/test system. A series of QCM sensors modified with PPy doped with different bromine containing anions and the regular chloride dopant were prepared and used for sensing of nitroexplosives. The design entailed a PPy-BPB modified QCM sensor with very low limit of detections for nitroexplosives including; 500 ppt (v) for TNT, 800 ppt (v) for PETN, 1 ppb (v) for RDX and 2 ppb (v)

Conjugated polymers for bioimaging and sensing chemical/biological reagents have received much attention owing to their outstanding photophysical properties. However, most conventional synthetic strategies result in aggregates of conjugated polymers with limited solubility in most common organic and aqueous solvents. Therefore, advancement in molecular design and synthetic pathways is required to tune the optical and solubility properties of the resulting conjugated polymers. Herein, a simple, general, and effective approach for the synthesis of water-soluble polypyrrole (PPy) is reported based on the chemical polymerization in the presence of a homologue series of dicarboxylic acids with different chain lengths as multifunctional dopant mo

Since the simple and accurate quantification of 2,4,6-trinitrotoluene (TNT) traces is still a challenge for analytical chemists, we employed a recently developed crossed-beam photothermal lens spectrometer for highly sensitive and selective determination of TNT through a well-known Meisenheimer complexation with n-butylamine (nBA). The colorless solution of TNT in dimethyl sulfoxide (DMSO) was changed to deep-red after the addition of nBA. Hence, we used a 532 nm diode laser as excitation source in photothermal lens investigations. All the instrumental parameters and chemical conditions such as chopper frequency, sample flow velocity, amine concentration and etc. were optimized. Photothermal lens measurements yielded a linear signal depende