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Towards green monitoring of antibiotics: a direct biochar-based electrochemical sensor for ampicillin detection in biomedical and environmental matrices

Macovei DG, Tertis M, Balla A, Kacsó I, Leoştean C, Tripon S, Suciu M, Cherecheş RM et al.

Talanta, 2026

Abstract

Antimicrobial resistance (AMR) represents a global health burden, requiring effective monitoring of antibiotic residues across the clinical-environmental chain. However, reference methods remain laboratory-based and solvent-intensive. To address this need in an ecologically responsible manner, this study exploits KOH-activated biochar derived from spent coffee grounds (BCK-KOH) as a screen-printed carbon electrode modifier for the direct detection of ampicillin (AMP); the corresponding non-activated material is denoted BCK. Characterization by N2 adsorption, FTIR, XPS and SEM-EDS revealed a 168-fold increase in BET surface area and substantial enrichment in surface carboxyl groups following activation. Modification with a PEI/BCK-KOH composite produced a ∼370 mV cathodic shift of the AMP oxidation signal compared with the unmodified electrode. Under optimized differential pulse voltammetry (DPV), the platform exhibited a linear range of 0.01-5 μM, an LOD of 3.3 nM, an LOQ of 10 nM and a sensitivity of 64.7 μA μM-1 (R2 = 0.997). The sensor showed acceptable interference tolerance toward the tested antibiotics and common endogenous compounds. Validation in artificial and ICU-patient serum, milk and water samples yielded recoveries of 88.5-111.4% with RSDs below 5.6% (n = 3), without pre-treatment. Because the LOQ closely matches the EU maximum residue limit (MRL) for AMP in milk, the platform enabled quantitative determination at approximately the MRL, 1.5×MRL and 2×MRL, with…

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