An electrochemical sensor for the determination of environmentally hazardous fungicide pyrimethanil in water and fruit samples† Chou-Yi Hsu, * a Tariq J. Al-Musawi, b Rahim Lataef, c Holya A. Lafta, d Dalal Abdullah Fatthi, e Ahmed S. Abed, f Salema K. Hadrawi, * g Maysm Barzan Talb, h Irfan Ahmad, i Safia Obaidur Rab i and Mohammad Y. Alshahrani i We developed a facile electroanalytical system for the rapid and sensitive detection of pyrimethanil through the modification of carbon paste electrode surface using the as-fabricated europium doped feather-type CuO nanoflowers (FT-Eu 3+ –CuO NF sensor). The peak current of pyrimethanil oxidation was elevated by the sensor due to the integration of appreciable electrochemical features of the modifier, which indicates the high ability of the modified electrode to enhance the sensitivity of pyrimethanil detection. The pyrimethanil sensor under the optimized setting had a broad linear dynamic range (0.001–800.0 mM) and a narrow limit of detection (0.18 nM). The practical applicability of the as-fabricated electrode was verified by sensing pyrimethanil in real samples; it also exhibited commendable specificity, stability and reproducibility. 1. Introduction Fungicides play a crucial role in food security around the world despite their threats. These agents have protective effects against pathogenic and problematic fungi in plants and agri- cultural crops. 1 One of the organic fungicides is 4,6-dimethyl-N- phenyl-2-pyrimidinamine, also called pyrimethanil or pyr- imethanil, belonging to the anilinopyrimidine category. This fungicide is extensively applied against various pathogenic fungi especially gray mold on agricultural crops. 2 According to the US Environmental Protection Agency (EPA), pyrimethanil residue was present on some vegetables and fruits. 3 The maximum residue limit (MRL in terms of mg kg -1 ) refers to the density of residue. The European Food Safety Authority (EFSA) declared that the acceptable daily intake (ADI) can be 0.17 mg kg -1 of body weight for pyrimethanil. 4 A pyrimethanil overdose can be associated with internal organ failure, respiratory paralysis, and even death. 5 Accordingly, there is a need for the development of fast, reliable and sensitive analytical techniques for pyrimethanil detection in various matrices. Hence, numerous techniques have been implemented to detect pyrimethanil, some of which are gas chromatography, high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry, surface-enhanced Raman spectroscopy and capillary electrophoresis. 6–10 Despite many advantages, all these approaches are associated with some disadvantages such as tedious sample preparation, high cost and limited real-time and on-site potency of determination. 11–16 Among these, great attention has been paid to the electro- chemical sensors for the quantication of pesticide residues because of their unique features such as cost-effectiveness, rapidity and high sensitivity. 17–25 The efficiency of the electro- chemical sensors largely depends on the electrode material, highlighting the need to obtain new electrode materials with good properties. To this end, noble metal materials and alloy metals are appropriate candidates for the surface modication of electrodes, but they have a high cost. However, transition metal oxides and metal oxide composites as new electrode materials can have lower costs. 26–34 Among various transition metal oxides and metal oxide composites, some advantages such as appreciable catalytic activity, high availability, low toxicity, inexpensiveness and green nature turned copper oxide (CuO) with a narrow band gap (1.4–1.7 eV) into promising catalyst for modifying the electrode a Department of Pharmacy, Chia Nan University of Pharmacy and Science, Tainan City 71710, Taiwan. E-mail: drchouyihsu@gmail.com b Building and Construction Techniques Engineering Department, Al-Mustaqbal University College, 51001 Hillah, Babylon, Iraq c College of Medical Technology, Al-Farahidi University, Iraq d Al-Nisour University College, Baghdad, Iraq e Department of Medical Laboratory Technics, AlNoor University College, Bartella, Iraq f Hilla University College, Department of Prosthetic Dental Technology, Babylon, Iraq g Refrigeration and Air-conditioning Technical Engineering Department, College of Technical Engineering, The Islamic University, Najaf, Iraq. E-mail: sahadrawi@ gmail.com h Mazaya University College, Iraq i Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia † Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d3ay02038j Cite this: DOI: 10.1039/d3ay02038j Received 18th November 2023 Accepted 24th January 2024 DOI: 10.1039/d3ay02038j rsc.li/methods This journal is © The Royal Society of Chemistry 2024 Anal. Methods Analytical Methods PAPER Published on 21 February 2024. Downloaded by Aston University on 3/4/2024 1:06:43 PM. View Article Online View Journal