Intense fluorescence from amitriptyline (AMT) was achieved after photochemical derivatization in an acidic aqueous medium (60 min of UV irradiation of solutions containing 0.027 mol L−1 HCl). After the reaction, fluorescence was significantly enhanced enabling the indirect fluorimetric determination of AMT in drugs and in a pharmacopoeia reference material. The limit of quantification (LOQ) was 1.3 × 10−7 mol L−1 and measurement uncertainty was about 6% at the concentrations close to the LOQ and less than 4% at higher concentrations. The mechanism of the photoreaction was proposed based on the identification of the products and on its kinetics. Studies aiming at the determination of AMT in human serum indicate the potential of the approach as a cheap and simple screening procedure for tricyclic antidepressants.
