Abstract: Here, we proposed an analytical approach based on the use of molecularly imprinted polymers - coated paper substrate (MIP-CPS) for paper spray ionization mass spectrometry (PS-MS) to improve its specificity. The new substrate developed was applied to detect and quantify dopamine, sarcosine butyric acid in synthetic human urine without derivatization or complex sample pre-treatments.Urinary levels of these metabolites can be correlated with several pathological conditions concerning heart disease, stress, neurological disorders, cancerous tumors, and AIDS. Calibration curves exhibited R2 > 0.99 for dopamine, sarcosine, and butyric acid. LODs and LOQs were found at μg L-1 (parts-per-billion) to dopamine and sarcosine, and pg L-1 (parts-per-trillion) to butyric acid. Precision and accuracy showed coefficients of variation and relative errors less than 18% for almost all analyses. Recovery test results ranged between 95.5 to 117.7%. Finally, we compared the analytical performance of MIP-CPS with the traditional paper substrate and ESI. MIP-CPS showed a superior performance to detect dopamine and avoiding the ionization suppression commonly from analysis of complex biological samples as urine