Voltammetric electronic tongue based on molecular sieves for identification of timolol pharmaceutical manufacturers

A voltammetric multisensory system of the «electronic tongue» type has been developed for the identification of manufacturers of timolol pharmaceutical preparations. The sensors are based on a glassy carbon electrode modified with composites of a polyelectrolyte complex of chitosan-N-succinyl chitosan (PEC) with zeolites (FAU, LTA) and silicoaluminophosphates (AFI). The choice of FAU, LTA zeolites and silicoaluminophosphate AFI is determined by their fundamentally different interaction mechanisms which together generate orthogonal analytical signals necessary for reliable identification. The developed composite sensor modifiers were studied using CV, DPV, EIS, SEM, ED-XRF, and X-ray diffraction methods. Using the chemometric methods PCA and SIMCA, we found that one‑ and two‑sensor systems fail to provide reliable recognition. In contrast, the three‑sensor system GCE/PEC@FAU, GCE/PEC@AFI, and GCE/PEC@LTA enabled correct classification of preparations from seven manufacturers, with no type I errors and type II errors not exceeding 20.0%. The proposed multisensory platform is simple to fabricate, low cost, and stable.