Nano-Molar Deltamethrin Sensor Based on Electrical Impedance of PAH/PAZO Layer-by-Layer Sensing Films

Abstract

This work reports a novel deltamethrin (DM) sensor able to detect nano-molar concentrations in ethanol solutions. The sensing layer consists of a thin film, obtained via a layer-by-layer technique, from alternate adsorption of poly(allylamine chloride) (PAH) and poly[1-[4-(3-carboxy-4-hydroxyphenylazo)-benzenesulfonamide)-1,2-ethanediyl]sodium salt] (PAZO) onto a solid support with interdigitaded gold electrodes. The sensor response, obtained from impedance spectroscopy measurements, was revealed to be linear with respect to the real part of impedance, taken at 100 Hz, when plotted as a function of the logarithm of deltamethrin molar concentrations in the micro- to nano-molar range. Sensor sensitivity was of 41.1 ± 0.7 kΩ per decade of concentration for an immersion time above 2 min and the reproducibility is approximately 2% in a binary solution of ethanol and deltamethrin. The main insight of this work concerns to DM detection limits as the sensor revealed to be able to detect concentrations below 0.1 nM, a value which is significantly lower than any reported in the literature and close what is appropriate for in situ environmental contaminant detection.

Polyelectrolyte Based Sensors as Key to Achieve Quantitative Electronic Tongues: Detection of Triclosan on Aqueous Environmental Matrices

“…TCS is one of the most studied pollutants in sensors development, as examples: a strand of carbon fibers with a voltammetric detector for high-performance liquid chromatography to detect TCS in rabbit serum and urine [32]; an electropolymerizing o-phenylenediamine on a glassy carbon electrode, using an amperometric sensor achieved a linear range of 2.0 × 10 −7 -3.0 × 10 −6 mol/L and a detection limit of 8.0 × 10 −8 mol/L [22]; a multiwall carbon nanotube film was developed for TCS detection using a electrochemical sensor with a linear range from 50 to 1.75 mg L −1 , and a limit of detection of 16.5 µg L −1 (57 nM) [33]. Recent studies [34][35][36][37][38] have reported well succeeded applications with sensors composed of layer-by-layer (LbL) thin-films, which were produced with polyelectrolytes and used to detect organic compounds (in ultrapure water matrices and methanol) using impedance measurements.…”

Detection and adsorption of Triclosan on sensors based on PAH/PVS thin-films

“…At acidic pH, TCS is nearly non-dissociated, hence an improved adsorption capacity was observed due to the increase of attractive interactions on the PAH layer (H-bond formation and hydrophobic interaction) [2, and references therein]. In addition, since protonated TCS molecules are more hydrophobic than the deprotonated anions, increased adsorption is likely to occur on the PAH and PVS layers at lower pH [10,11]. It is important to note that the highest absorbances of TCS onto (PAH/PVS) 10 /PAH and (PAH/PVS) 10 both at 232 nm and 280 nm were at pH 5.68 and 3.7, respectively.…”

Flexible Carbon Electrodes for Electrochemical Detection of Bisphenol-A, Hydroquinone and Catechol in Water Samples

“…The detection of pollutant traces is crucial for guaranteeing the safety of public water supply and aquifers, which can be contaminated by pesticides [1], industrial products, personal hygiene pharmaceutical products (PPCPs) [2][3][4][5], and other emerging contaminants [6]. Among the latter contaminants, attention has been paid to plastic packaging containing bisphenol A (2,2-bis (4-hydroxyphenyl) propane) (BPA), a poorly water-soluble compound (5.2 × 10 −4 mol L -1 ) used in manufacturing [7] of polycarbonate plastics and epoxy resins [4,8,9].…”