“SOLID AS SOLVENT” - NOVEL TECHNIQUE FOR SPECTROPHOTOMETRIC ESTIMATION OF NAPROXEN TABLETS USING SOLIDS (EUTECTIC LIQUID OF PHENOL AND METFORMIN HYDROCHLORIDE) AS SOLUBILIZING AGENTS (MIXED SOLVENCY CONCEPT)
R K Maheshwari*, Payal Jain, Deepak Kumar, Devika Parkhe
ABSTRACT
A large number of researchers are doing much work to give eco-friendly solutions for control of the pollution and toxicity caused by most of the organic solvents. In this field, Maheshwari has given a nice concept, known as mixed-solvency concept. Innumerable solvent systems can be developed by the application of this concept. In the opinion of Maheshwari, each substance possesses solubilizing power. He has given several eco-friendly methods in the area of drug
estimations and formulations precluding the use of toxic organic solvents. The present research work also provides a novel method to estimate spectrophotometrically, the naproxen drug, in tablet formulations without the help of organic solvent. The present investigation is an attempt to show that solids can also be wisely used to act as solvent precluding the use of organic solvents. The main objective of the present study is to demonstrate the solvent action of solid. In the present study, a eutectic liquid (PMHCl 41) obtained by triturating phenol crystals and metformin hydrochloride in 4:1 ratio on weight basis was employed to extract (dissolve) naproxen from fine powder of tablets. Distilled water was used for dilution purpose to carry out spectrophotometric estimation at 331 nm without utilizing any organic solvent. The solubility of naproxen in distilled water at room temperature was found to be 0.9 mg/ml while the solubility of naproxen in PMHCl 41 was more than 90 mg per ml (of PMHCl 41). Proposed spectrophotometric analytical method is novel, rapid, free from toxicity of organic solvent, accurate and reproducible. The recovery studies and statistical data confirmed the accuracy, reproducibility and precision of the proposed anlytical method. The presence of phenol, metformin hydrochloride and the tablet excipients did not interfere in the spectrophotometric estimation at 331 nm. Phenol and metformin hydrochloride do not interfere above 300 nm. In future the solids (melted solids, eutectic liquids etc) shall also be utilized to solubilise the reactants to carry out organic synthesis, extractions of active constituents from herbal sources etc.
Keywords: Mixed-solvency concept, naproxen, phenol, metformin hydrochloride, spectrophotometric analysis, eutectic liquid.
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