Analysis of Levothyroxine in Pharmaceutical Formulation by a Novel Levothyroxine Potentiometric Membrane Sensor

Observation of the patients used levothyroxine tablets but still have problem with their thyroid, leads to analysis of pharmaceutical formulation in the first step. Common instrumental methods for the active ingredient analysis of different pharmaceutics are timeconsuming and pricy and require a skilled operator. In this study, for the first time, an electrochemical sensor which is capable of evaluating the active ingredient of Levothyroxine in formulations is introduced. The proposed sensor, which is a PVC membrane electrode, offers advantages of rapidity, inexpensively, and portability. The sensor responds based on ion-exchange mechanism. Levothyroxine-Hexadecyltrimethylammonium ion-pair (LEVHTA) was employed as a sensing element in construction of the membrane electrode. PVC membrane electrode was made after series of experiments. The best PVC membrane electrode performance was achieved by a membrane composition of 30% PVC, 60% DBP, and 7% LEV-HTA ion-pair. The proposed method was successfully applied in determination of levothyroxine in some pharmaceutical formulations. Five samples from the vary batches, coded differently, were sent for high performance liquid chromatography (HPLC) analysis. The results of two methods were compared using parametric tests. Pearson correlation test was used to assess the correlation between these findings. A strong correlation was found between the active ingredient content measured using electrochemical sensor and official method (HPLC) (ρ=0.98 P<0.05).