Capmatinib (CMB) monitoring in biological fluids is critical for evaluating its pharmacokinetics, optimizing
dosing, and minimizing toxicity. Accurate measurement is essential for ensuring therapeutic efficacy,
enabling personalized treatment, and preventing adverse effects. Given the variability in patient
metabolism and excretion, regular monitoring helps maintain CMB levels within the therapeutic range,
improving treatment outcomes and minimizing the risk of drug resistance. This work presents an
economical and energy-efficient strategy for preparing highly luminescent nitrogen-doped carbon dots
(NCDs), employing 2,5-dihydroxy-1,4-benzoquinone alongside triethylenetetramine. The synthesized
NCDs demonstrated excellent photostability and a high fluorescence quantum yield of 38.72%. Upon the
addition of CMB, concentration-dependent fluorescence quenching was observed at 515 nm, which was
attributed to the inner filter effect (IFE), with LOD of 3.6 nM. The NCDs exhibited high selectivity in
detecting CMB, with minimal cross-reactivity from simultaneously present compounds. Recovery studies
in real biological samples yielded rates between 97.4% and 105.3%, and RSDs were consistently below
4.11%. These results demonstrate the method's precision, reproducibility, and potential for reliable CMB
detection in complex biological matrices.