Romanian Society of Pharmaceutical Sciences
 

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A NEW NON-EXTRACTIVE ION-PAIR SPECTROPHOTOMETRIC METHOD FOR THE ASSAY OF ALBENDAZOLE

MARINELA FLOREA 1, IOANA CLEMENTINA CONSTANTINESCU 1*, MIHAELA VIOLETA GHICA 2, LĂCRĂMIOARA POPA 2, CORINA-CRISTINA ARAMĂ 1, ANGELA NEDELCU 1

“Carol Davila” University of Medicine and Pharmacy, Faculty of Pharmacy, 6 Traian Vuia Street, 020956, Bucharest, Romania
1 .Department of Analytical Chemistry,
2 .Department of Physical and Colloidal Chemistry

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The paper presents a new non-extractive spectrophotometric method for the assay of albendazole (ABZ) as ion pair with Congo red (CR). A soluble and stable ion pair (ABZ-CR) with an absorption maximum at 294 nm was obtained using a 2·10-8 M CR concentration and Britton Robinson (BR) buffer with pH = 2.5. The method is linear in the range 2.5 - 4.7 µg/mL, with limits of detection and quantification of 0.09 µg/mL and 0.28 µg/mL, respectively. The proposed method was applied to the assay of ABZ in bulk pharmaceutical substance. Because CR is a dye with pharmacological applications used as model in biochemical studies, the research also focused on the mechanism of interaction with ABZ. Spectral changes and physico-chemical constants (conductivity, dielectric constant) indicated that ABZ-CR ion pairing takes place at the surface of CR aggregates by electrostatic and charge transfer interactions.