Analysis of Terlipressin via Ion-Pairing With Eosin Y as a Spectrofluorometric and Spectrophotometric Probe

Two green analytical procedures were designed to quantify terlipressin in bulk material and pharmaceutical dosage forms. In both procedures, terlipressin interacts with Eosin Y through ion-pair formation between the drug's protonated amino group and the anionic dye under controlled experimental settings. In the fluorimetric procedure, the resulting complex suppresses the native fluorescence of Eosin Y. Measurements are carried out in acetate buffer (pH 3.3), where the decrease in fluorescence is directly related to terlipressin concentration across 50-500 ng/mL. In the spectrophotometric procedure, the ion-pair complex is quantified by measuring absorbance at 550 nm, providing a linear response over 1-10 μg/mL. Both methods were validated and found to meet international analytical guidelines for linearity, accuracy, precision, and robustness. Their environmental impact was also evaluated using established "greenness" assessment tools, and the results showed good ecological performance because the procedures mainly use aqueous solutions. Overall, these methods are simple and inexpensive options for routine quality control of terlipressin, offering practical alternatives to more complex chromatographic techniques.