Simultaneous detection of ammonium and nitrate in environmental samples using on ion-selective electrode and comparison with portable colorimetric assays

Simple, robust, and low-cost nitrate-and ammonium-selective electrodes were made using substrate prepared from household materials. We explored phosphonium-based ILs and poly (methyl methacrylate)/poly(decyl methacrylate)(MMA-DMA) copolymer as matrix materials alternative to classical PVC-based membranes. IL-based membranes showed suitability only for nitrate-selective electrode exhibiting linear concentration range between 5.0 × 10−6 and 2.5 × 10−3 M with a detection limit of 5.5 × 10−7 M. On the other hand, MMA-DMA—based membranes showed suitability for both ammonium-and nitrate-selective electrodes, and were successfully applied to detect NO3− and NH4+ in water and soil samples. The proposed ISEs exhibited near-Nernstian potentiometric responses to NO3− and NH4+ with the linear range concentration between 5.0 × 10−5 and 5.0 × 10−2 M (LOD = 11.3 µM) and 5.0 × 10−6 and 1.0 × 10−3 M (LOD = 1.2 µM), respectively. The power of ISEs to detect NO3− and NH4+ in water and soils was tested by comparison with traditional, portable colorimetric techniques. Procedures required for analysis by each technique from the perspective of a non-trained person (e.g., farmer) and the convenience of the use on the field are compared and contrasted

A nanocomposite optosensor containing carboxylic functionalized multiwall carbon nanotubes and quantum dots incorporated into a molecularly imprinted polymer for highly selective and sensitive detection of ciprofloxacin

A nanocomposite optosensor consisting of carboxylic acid functionalized multiwall carbon nanotubes and CdTe quantum dots embedded inside a molecularly imprinted polymer (COOH@MWCNT-MIP-QDs) was developed for trace ciprofloxacin detection. The COOH@MWCNT-MIP-QDs were synthesized through a facile sol-gel process using ciprofloxacin as a template molecule, 3-aminopropylethoxysilane as a functional monomer and tetraethoxysilane as a cross-linker at a molar ratio of 1:8:20. The synthesized nanocomposite optosensor had high sensitivity, excellent specificity and high binding affinity to ciprofloxacin. Under optimal conditions, the fluorescence intensity of the optosensor decreased in a linear fashion with the concentration of ciprofloxacin and two linear dynamic ranges were obtained, 0.10–1.0 g L-1 and 1.0–100.0 g L-1with a very low limit of detection of 0.066 g L-1 .The imprinting factors of the two linear range were 17.67 and 4.28, respectively. The developed nanocomposite fluorescence probe was applied towards the determination of ciprofloxacin levels in chicken muscle and milk samples with satisfactory recoveries being obtained in the range of 82.6 to 98.4%. The results were also in good agreement with a HPLC method which indicates that the optosensor can be used as a sensitive, selective and rapid method to detect ciprofloxacin in chicken and milk sample. [This version of the abstract is from the authors' manuscript and is not the final published version

Simultaneous detection of ammonium and nitrate in environmental samples using on ion-selective electrode and comparison with portable colorimetric assays

Simple, robust, and low-cost nitrate-and ammonium-selective electrodes were made using substrate prepared from household materials. We explored phosphonium-based ILs and poly (methyl methacrylate)/poly(decyl methacrylate)(MMA-DMA) copolymer as matrix materials alternative to classical PVC-based membranes. IL-based membranes showed suitability only for nitrate-selective electrode exhibiting linear concentration range between 5.0 × 10−6 and 2.5 × 10−3 M with a detection limit of 5.5 × 10−7 M. On the other hand, MMA-DMA—based membranes showed suitability for both ammonium-and nitrate-selective electrodes, and were successfully applied to detect NO3− and NH4+ in water and soil samples. The proposed ISEs exhibited near-Nernstian potentiometric responses to NO3− and NH4+ with the linear range concentration between 5.0 × 10−5 and 5.0 × 10−2 M (LOD = 11.3 µM) and 5.0 × 10−6 and 1.0 × 10−3 M (LOD = 1.2 µM), respectively. The power of ISEs to detect NO3− and NH4+ in water and soils was tested by comparison with traditional, portable colorimetric techniques. Procedures required for analysis by each technique from the perspective of a non-trained person (e.g., farmer) and the convenience of the use on the field are compared and contrasted

Sol-gel based sensor for selective formaldehyde determination

We report the development of transparent sol–gels with entrapped sensitive and selective reagents for the detection of formaldehyde. The sampling method is based on the adsorption of formaldehyde from the air and reaction with β- diketones (for example acetylacetone) in a sol–gel matrix to produce a yellow product, lutidine, which was detected directly. The proposed method does not require preparation of samples prior to analysis and allows both screening by visual detection and quantitative measurement by simple spectrophotometry. The detection limit of 0.03 ppmv formaldehyde is reported which is lower than the maximum exposure concentrations recommended by both the World Health Organisation (WHO) and the Occupational Safety and Health Administration (OSHA). This sampling method was found to give good reproducibility, the relative standard deviation at 0.2 and 1 ppmv being 6.3% and 4.6%, respectively. Other carbonyl compounds i.e. acetaldehyde, benzaldehyde, acetone and butanone do not interfere with this analytical approach. Results are provided for the determination of formaldehyde in indoo

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Thailand Research Fun

Polyaniline-coated magnetite nanoparticles incorporated in alginate beads for the extraction and enrichment of polycyclic aromatic hydrocarbons in water samples

<p>A magnetic solid-phase extraction sorbent consisting of polyaniline-coated magnetite nanoparticles entrapped in alginate beads (PANI/alginate/Fe₃O₄) was successfully synthesised and applied for the extraction and preconcentration of polycyclic aromatic hydrocarbons (PAHs) in water samples. The magnetite nanoparticles helped to provide an easy and rapid isolation of the sorbent from the sample solution using an external magnet. The alginate beads helped to increase the surface area for polyaniline coating. The polyaniline-coated alginate/magnetite composite helped to increase the extraction efficiency due to the π–π interactions between the polyaniline and the PAHs. Various parameters that affected the extraction efficiencies were optimised including the polymerisation time, the amount of sorbent, sample pH, extraction time, ionic strength, and desorption conditions. Under the optimal conditions, a linear response was achieved in the concentration range of 0.040–50.0 µg L⁻¹, and the limit of detection was 0.010 µg L⁻¹. This simple, convenient, cost-effective, and environmentally friendly method was successfully applied for the extraction and enrichment of PAHs in water samples. The recoveries ranged from 86.0% to 97.8% with a relative standard deviation <10 %.</p

Microbial BOD sensor for monitoring treatment of wastewater from a rubber latex industry

A cell-based biosensor system was designed for monitoring an anaerobic process for treatment of high biochemical oxygen demand (BOD) levels in wastewater samples from a factory processing concentrated rubber latex. The BOD biosensor used immobilized mixed culture of microorganisms as the biological sensing element and an oxygen electrode as the transducer. The assay principle is based on the determination of the oxygen consumption rate caused by microbial respiration. Synthetic wastewater according to the OECD specifications was used as standard solution for calibration of the BOD biosensor. Response time of the sensor was 10-15 min. The BOD of the influent and the effluent from an anaerobic reactor was measured using both the cell-based biosensor system and a standard method (BOD5). Good agreement was achieved between the results from the two assay methods with a percentage difference of less than 10%. However, when exposing the mixed culture to wastewaters from other industrial plants the agreement between the results of the two assays was poor. The anaerobic treatment of the wastewater from the concentrated latex process resulted in a COD removal efficiency of 97% at a hydraulic retention time (HRT) of 50 days. The BOD biosensor was successfully applied to off-line and on-line monitoring of the anaerobic reactor treatment process