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

Congreso; 1ª Reunión Internacional de Ciencias Farmacéuticas; 2010

Introduction Amiloride (AMI) and furosemide (FUR) are 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 were placed in filter holder and 10 mL 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 2.7. Then, sample and standards solutions were introduced into the spectrofluorometer and the fluorescent emission was measured at lem = 415 nm using lex = 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. Both drugs can be spectrofluorimetrically determined, on the membrane and in the filtered solution, respectively (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. A novel application of immobilization on membranes for the separation and spectrofluorimetric quantification of amiloride and furosemide in pharmaceutical samples Anal Chim Acta 661 (2010): 85-90.