Development of a glucose/tartaric acid/glycerol based ternary natural deep eutectic solvent modified carbon paste electrode for carbendazim sensing

In this work, a novel electrochemical sensor based on a ternary natural deep eutectic solvent (t_NADES) modified carbon paste electrode was developed to quantify carbendazim in tap water samples. Ternary NADES (t_NADES) were prepared from D (+) glucose, L (+) tartaric acid as a base binary mixture with ethylene glycol (t_NADES1), glycerol (t_NADES2) or water (t_NADES3) as a third component. When characterized by FTIR-ATR, all t_NADES presented shifts at CO stretching wavenumber confirming the new formed hydrogen bonds interactions. The carbon paste electrode modified with t_NADES2_–10%, D(+) glucose: L(+) tartaric acid: glycerol molar ratio (1:1:5) presented the best performance among all t_NADES evaluated due to increased cohesion of the graphitic sheets of t_NADES observed at SEM-FEG images. The addition of t_NADES to the carbon paste also reduces the hydrophobic character of the CPEs. The t_NADES modified electrode presented higher peak currents for both electrochemical probe and carbendazim and lower charge transfer resistance when compared to the bare electrode. The calibration curve for carbendazim presented linear correlation in the concentration range from 1.0 to 15.0 μmol L⁻¹, with LOD of 0.57 μmol L⁻¹. The proposed method proved to be accurate and selective, as observed from intra-day repeatability studies (RSD < 5 %) and the reproducibility of electrode preparation (RSD <5 %). The modified electrode allowed a very accurate recovery for carbendazim in tap water samples, with recovery values between 99.2 % and 101.9 %/ (n = 3).