Maprotiline hydrochloride is a tetracyclic antidepressant, which is as a selective inhibitor of the reuptake of the neurotransmitter norepinephrine from the synaptic cleft into the presynaptic nerve cell used in the treatment of depression and associated anxiety. Potentiometry, unlike various forms of liquid and gas chromatography, represents a cheaper technique that does not require sample pretreatment and enables optimal possibilities for the studies of analytical, pharmaceutical, and biological samples. Due to their excellent mechanical, thermal and electrical properties, the inclusion of graphite and other carbon allotropes in the composition of electrochemical sensors is becoming increasingly common. This master’s thesis presents the basis for the optimization of a chemically modified electrode made of carbon paste for the potentiometric determination of maprotiline hydrochloride. At the beginning of the experimental work, it was determined that graphite and dibutyl phthalate as a binder would be present in the paste in a 1:1 ratio. The binder must be lipophilic so that the paste, as part of the electrode immersed in a solution, maintains its shape. It is also involved in controlling the balance between the ion pair and primary ions in the paste. Minor part of the paste composition consists of the ion pair, which has the main influence on the selectivity of the ion-selective electrode due to its affinity for the analyte. I used maprotiline-tetraphenylborate, maprotiline-phosphotungstate, and maprotiline-phosphomolybdate as ion pairs. The response of the ion-selective electrode can be further improved by a lipophilic additive, that through repulsion between ions of similar charges prevents co-extraction of ions into the paste during the extraction of the analyte ions. As a lipophilic additive I tested tetrabutylammonium tetraphenylborate and sodium tetraphenylborate. As a final addition to the pastes to improve their response characteristics, I added reduced graphene oxide, N-doped reduced graphene oxide and N-doped reduced nanoribbon graphene oxide. The carbon paste electrode that exhibited the best response characteristics among those tested was used for further potentiometric characterization. This involved examining the influence of pH on the response characteristics, determining the response time, and reversibility. The electrode was also used for the potentiometric determination of maprotiline in analytical solutions, Ludiomil tablets solutions and urine with the addition of maprotiline, using the standard addition method and potentiometric titration.
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