Electrochemical Determination of Nitroguanidine among Other Explosives Using Polymerized 2‑Nitrophenol/Reduced...

In this study, a novel sensor working electrode was fabricated by functionalizing a glassy carbon (GC) electrode surface with electrochemically reduced graphene oxide (ERGO) and poly-2-nitrophenol (P2NP, electrochemically polymerized, used as a hydrogen-bonding substrate) using the proposed square-wave voltammetry (SWV) method toward the highly selective and sensitive electrochemical sensing of nitroguanidine (NG), a friction- and impact-insensitive high explosive increasingly used in energetic formulations, even in the presence of other types of energetic materials. NG showed a characteristic reduction peak at approximately -1.27 V. A linear response was obtained between 0.5 and 100 mg L^-1 (4.80 × 10^-6-9.61 × 10^-4 mol L^-1), and the limit of detection (LOD) was found as 0.12 mg L^-1 (1.15 × 10^-6 mol L^-1). The developed GC/ERGO/P2NP sensor electrode successfully determines NG in both synthetic and real energetic material mixtures (20-fold) with high recovery rates. The sensor maintained its high selectivity (20 mg L^-1 NG) even with the addition of potential soil interferents at a 50-fold excess (10-fold for Fe³⁺, Pb²⁺, and Cu²⁺) including Cl^-, SO₄ ^2-, NO₂ ^-, NO₃ ^-, NH₄ ⁺, K⁺, Na⁺, Ca²⁺, and Mg²⁺, and electroactive camouflage materials (10-fold) such as paracetamol, caffeine, acetylsalicylic acid, aspartame, d-glucose, and detergent. Finally, clay soil samples contaminated with NG were analyzed using the proposed method, and the results were statistically compared with LC-MS using Student's t-test and F-test, confirming its reliability for real-world environmental monitoring.