Flexible Miniaturized Electrochemical Sensors Based on Multiwalled Carbon Nanotube-Chitosan Nanomaterial for Determination of Nitrite in Soil Solutions

Flexible screen-printed electrodes (SPE) were modified in a simple manner with different composite nanomaterials based on carbon allotropes, polymers, and metallic nanoparticles, for amperometric detection of nitrites soil. Multiwalled nanotubes (MWCNT), chitosan (CS), silver nanoparticles (AgNPs), 1,8-diaminonaphthalene (1,8-DAN), sol-gel (SG) matrix used modification the paste working electrodes. Sensitive selective nitrite was achieved by using MWCNT-CS-modified sensor, acetate buffer at pH 5, an applied potential 0.58 V vs. Ag/AgCl. The MWCNT-CS-based sensor displayed specific sensitivity 204.4 mA·M−1·cm−2, limit 2.3 µM (S/N = 3) linear range up to 1.7 mM, showing good stability, reproducibility, selectivity towards other interfering species. A miniaturized portable system developed flexible electrochemical sensors dedicated samples soil solutions extracted suction lysimeters.