A NOVEL APPLICATION OF IMMOBILIZATION ON MEMBRANES FOR THE SEPARATION AND SPECTROFLUORIMETRIC QUANTIFICATION OF AMILORIDE AND FUROSEMIDE IN PHARMACEUTICAL SAMPLES AND URINE

PERALTA CECILIA MARIANA; FERNÁNDEZ, LILIANA PATRICIA; MASI, ADRIANA NOEMÍ

Córdoba, Argentina

Congreso; 1ª Reunión Internacional de Ciencias Farmacéuticas; 2010

A NOVEL APPLICATION OF IMMOBILIZATION ON MEMBRANES FOR THE SEPARATION AND SPECTROFLUORIMETRIC QUANTIFICATION OF AMILORIDE AND FUROSEMIDE IN PHARMACEUTICAL SAMPLES AND URINE Peralta CM1, Fernández LP1,2, Masi AN∗1,2 1 Instituto de Química de San Luis (INQUISAL-CONICET). 2 Área de Química Analítica. Facultad de Química, Bioquímica y Farmacia. Chacabuco y Pedernera. Universidad Nacional de San Luis. 5700 - San Luis. ARGENTINA. Introduction Amiloride (AMI) and furosemide (FUR) are drugs widely used in different types of diuretics. These pharmaceutical formulations are supplied in numerous therapeutical indications, such as arterial hypertension, cardiac insufficiency, and hepatic cirrhosis since they rise the rate of urine formation, increasing the excretion of electrolytes, especially sodium, chloride and water (1,2). Materials and methods Polyamide membranes Millipore were placed in filter holder and 10mL of sample solutions at pH 11 were filtered through it using a positive pressure, keeping a flow rate of approximately 4 mL min−1. Filtered solutions were reserved. After the membrane was dried, the disc was placed in a solid sample holder, and the AMI fluorescence spectrum was scanned. The excitation and emission wavelengths were adjusted at 365 and 406 nm, respectively. For FUR determination, the filtered solutions were adjusted at pH 2.7. Then, sample and standards solutions were introduced into the spectrofluorometer and the fluorescent emission was measured at λem 415 nm using λex 237 nm. Results FUR and AMI exhibit overlapped fluorescent spectra and urine produces background fluorescence that precludes the direct determination of these diuretics by conventional fluorimetry. This problem could be solved separating the analytes through a polyamide membrane. The optimum separation conditions were obtained filtering at pH 11, at which AMI keeps as neutral specie retained by the polyamide membrane, while the anionic form of FUR, remains in solution (3). The calibration graphs are linear in the range 3.20×10−4 to 0.8 µg mL−1and 1.33×10−3 to 4.0µg mL−1 for AMI and FUR, respectively, with a detection limit of 9.62×10−5 and 4.01×10−4 µg mL−1 (S/N= 3). Conclusions The present study demonstrates the feasibility of using a membrane as a novel support for solid-phase extraction procedures, focused on AMI and FUR separation and determination. Both sensitivity and selectivity are, then, substantially increased due to both the preconcentration on the support and the separation of the analyte from the matrix. Acknowledgments The authors gratefully appreciate the financial support from INQUISAL-CONICET (Instituto de Química de San Luis – Consejo Nacional de Investigaciones Científicas y Tecnológicas), FONCYT (Fondo Nacional de Ciencia y Tecnología), and National University of San Luis (Project 22/Q828). References 1. Foye WO, Lemke TL, Williams DA, Principles of Medicinal Chemistry, 4th ed., USA: Williams and Wilkins, 1995, p. 405. 2. Gringauz A, Introduction to Medicinal Chemistry—How Drugs Act and Why, New York, USA: Wiley-VCH Inc., 1997, p. 461–462. 3. Peralta CM, Fernández LP, Masi AN. Anal Chim Acta 661 (2010): 85-90. ∗ Corresponding author at: Instituto de Química de San Luis (INQUISAL-CONICET), Chacabuco y Pedernera, 5700 - San Luis, Argentina. Tel.: +54 2652 425385; fax: +54 2652 430224. E-mail address: amasi@unsl.edu.ar (A.N. Masi).