Polyamic acid (PAA) immobilized on glassy carbon electrode (GCE) as an electrochemical platform for the sensing of tuberculosis (TB) antibodies and hydrogen peroxide determination

Organochlorine pesticide residues in agricultural draining water in Tunisia

Organochlorines pesticides (OCPs) are persistent organic pollutants known by their persistence, their ability to bioaccumulate in the food chain and by their toxicity. This work aims to analyze pesticides in draining water samples taken from two different regions from Tunisia. A liquid-liquid extraction method proposed by the International Atomic Energy Agency (IAEA) has been adopted for the extraction of OCPs from draining water. The analysis of these compounds was carried out with a gas chromatography coupled to mass spectrometry. Eight draining water sample was analyzed from the region of Kebili and levels of OCPs ranged between ND and 3.415 ng L^-1. Four draining water samples were sampled from the region of Cap Bon and levels of OCPs in draining water varied between 14.955 and 59.305 ng L^-1. The concentration of OCPs in draining water didn't exceed the limits standardized by the regulations for drainage water, which makes possible the reuse of this water for agricultural purposes after having undergone a secondary treatment.

Spectroscopy, Morphology, and Electrochemistry of Electrospun Polyamic Acid Nanofibers

Polyamic acid (PAA) nanofibers produced by using the electrospinning method were fully characterized in terms of morphology and spectroscopy. A PAA nanofiber–modified screen-printed carbon electrode was applied to the detection of selected sulfonamides by following an electroanalytical protocol. The polyamic acid (PAA) nanofibers were characterized using Fourier transform infrared (FTIR) spectroscopy to study the integrity of polyamic acid functional groups as nanofibers by comparing them to chemically synthesized polyamic acid. A scanning electron microscope (SEM) was used to confirm the morphology of the produced nanofibers and 3D arrangement at the electrode interface. The Brunauer–Emmett–Teller (BET) method was used to determine the surface area of the nanofibers. Atomic force microscopy (AFM) was used to study the porosity and surface roughness of the nanofibers. Electrochemical evaluation based on diffusion-controlled kinetics was applied to determine the number of electrons transferred in the system, the surface concentration of the deposited PAA thin film (2.14 × 10⁻⁶ mol/cm²), and the diffusion coefficient (D_e) for the PAA nanofiber–modified screen-printed carbon electrode (9.43 × 10⁻⁷ cm⁻²/s). The reported LODs for sulfadiazine and sulfamethazine detection are consistent with requirements for trace-level monitoring by early warning diagnostic systems.