ORIENTAL JOURNAL OF CHEMISTRY www.orientjchem.org An International Open Free Access, Peer Reviewed Research Journal ISSN: 0970-020 X CODEN: OJCHEG 2016, Vol. 32, No. (3): Pg. 1545-1550 Identification and Characterization of Solid Binary System of Quercetin-Nicotinamide ERIZAL ZAINI*, DILLAH AZHARI and LILI FITRIANI Faculty of Pharmacy, Andalas University, Kampus Limau Manis Padang - 25163, Indonesia. *Corresponding author E-mail: erizal@ffarmasi.unand.ac.id http://dx.doi.org/10.13005/ojc/320330 (Received: May 18, 2016; Accepted: June 27, 2016) ABSTRACT Preparation of binary system quercetin-nicotinamide and the solubility evaluation have been conducted in this study. Binary system was prepared by solvent evaporation technique and physical mixture was used as comparison. The aim of this study is to analyze the type of interaction and to investigate the solubility of quercetin-nicotinamide produced. Identification of binary system interaction were done using Powder X-ray diffraction (PXRD), Differential Thermal Analysis (DTA), Infrared spectroscopy (IR), Scanning Electron Microscopy (SEM), and solubility test. Determination of quercetin was done in ethanol:water (1:1) by High Performance Liquid Chromatography (HPLC) using acetonitrile:phosphate acid 0,1% (55:45) as mobile phases. Diffractogram powder X-ray showed a decrease in the peak intensity, but did not show a new crystalline phase. DTA thermal analysis showed a decrease in the melting point of the binary system compared to quercetin, which likely eutectic mixture was formed. SEM results indicated the changes in the morphology of the crystal compared to pure components. FT IR analysis showed a shift wavenumber of the spectrum quercetin and nicotinamide. Interaction between these compound showed that the conglomerated form (simple eutectic) between two crystalline phases. The solubility of binary system quercetin-nicotinamide increased compared to intact quercetin. Solubility of quercetin, physical mixture and binary system quercetin nicotinamide were 0.294±0.005 mg/mL, 0.338±0.004 mg/mL, and 0.419±0.001 mg/mL, respectively. In conclusion, the solubility increased after the formation of binary system quercetin- nicotinamide. Keywords: quercetin, nicotinamide, interaction, binary system, eutectic. INTRODUCTION Quercetin is a flavonoid polyphenol compound, which is still interesting to study due to several pharmacological activities 1 . However, quercetin has a low solubility in water, causing limitations in the process of absorption and effect on bioavailability in the body 2 . Several methods have been conducted to improve the solubility and dissolution rate of quercetin such as formation of inclusion complexes with cyclodextrins 3 , manufacture of solid dispersions 1 , and formation of nanoparticles 4,5 . Efforts to improve the solubility of drug compounds which are poorly soluble in water