Methylisothiazolinone response on disposable electrochemical platforms modified with carbon, nickel or gold-based nanomaterials.

Screen-printed carbon electrodes (SPCE) were modified with nanocomposite membranes based on polystyrene sulfonate (PSS) or poly(diallyldimethylammonium) (PDDA) matrices and different nanomaterials. Carbon nano-powders (CnP), carbon nano-fibers (CnF) and multi-walled carbon nano-tubes (MWCNTs) were incorporated on PSS matrix. Nickel was incorporated by ion exchange in PSS-CnP composite membranes. Gold nanoparticles (AuNp) were photochemically and electrochemically synthesised and introduced into PDDA membranes. The electrochemical behaviour of methylisothiazolinone (MIT) using these modified electrodes was studied by cyclic voltammetry in 0.1 mol L⁻¹ NaOH. No electrochemical response is obtained on PSS-nanocarbon transducers at the assayed conditions. The nickel-based transducers allow the MIT identification but not quantification. Using AuNp-based electrochemical transducers, it is observed that in presence of MIT, the electron transfer for AuNp reduction is inhibited, and an oxidation peak appears at + 0.45 V, indicating an interaction between MIT and AuNp on the electrode surface. These facts support the usefulness of the AuNp-based electrodes for the determination of MIT. The intensity of the anodic peak observed at + 0.45 V vs. Ag/AgCl was used as analytical signal for MIT determination. A linear relationship between anodic peak current and MIT concentration is observed in the range 8.7 to 36 mg L⁻¹ using the transducer prepared by incorporating gold into the PDDA membrane by ion exchange and synthesising AuNp electrochemically. For this electrode, the limit of detection is 2.6 mg L⁻¹ and the reproducibility, expressed as relative standard deviation (RSD), is lower than 7%. [ABSTRACT FROM AUTHOR]