Voltammetric determination of fentanyl in biological matrices using an unmodified disposable pencil graphite electrode: Experimental and theoretical study
Forensic Chemistry, vol.50, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 50
- Publication Date: 2026
- Doi Number: 10.1016/j.forc.2026.100753
- Journal Name: Forensic Chemistry
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Keywords: Density functional theory, Differential-pulse voltammetry, Fentanyl, Greenness, Pencil graphite electrode, Square-wave voltammetry
- Gazi University Affiliated: Yes
Abstract
Disposable pencil graphite electrodes (PGE) were evaluated as an unmodified disposable platform for voltammetric determination of fentanyl (FEN) in human serum and urine. Square-wave voltammetry (SWV) and differential-pulse voltammetry (DPV) provided reproducible signals with low background current. The analytical response was optimized by screening buffer media over pH 4.00–10.00, where the highest peak current observed in phosphate buffer at pH 8.00. Under the optimized conditions, calibration plots were linear over 8.00 × 10−7–1.00 × 10−4 M, with limits of detection of 9.41 × 10−8 M (SWV) and 2.63 × 10−7 M (DPV). For biological sample applicability, separate calibration lines were constructed for both human serum and urine, confirming strong linearity and sensitivity. The method showed a moderately green profile and was practically suitable for repeated use in standard analytical workflows. Greenness assessment revealed strong precision and linearity in human serum but indicated matrix-related challenges in urine samples. To rationalize the pH-dependent electrochemical behavior, density functional theory calculations were performed for neutral and protonated fentanyl using the ωB97X-D/def2-TZVP level with a polarizable continuum model for water. Molecular docking (AutoDock Vina) indicated favorable binding to human serum albumin (HSA; PDB ID: 2BXD) with a predicted affinity of −9.01 kcal/mol, supporting potential matrix-related interactions. This proposed approach enables sub-micromolar FEN determination using a simple disposable electrode while providing computational insight that complements the experimental optimization.