Application of a Magnetic Molecularly Imprinted Polymer for the Removal of Sulfanilamide as Major Impurity in Eye Drops
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Pharmaceutical Chemistry Journal, Vol. 54, No. 9, December, 2020 (Russian Original Vol. 54, No. 9, September, 2020)
APPLICATION OF A MAGNETIC MOLECULARLY IMPRINTED POLYMER FOR THE REMOVAL OF SULFANILAMIDE AS MAJOR IMPURITY IN EYE DROPS (SULFACETAMIDE) Hamid Hashemi-Moghaddam1,* and Maryam Shabestani-Trojeni2 Original article submitted August 8, 2017. Magnetic molecularly imprinted polymers (MIPs) have been synthesized for the removal of sulfanilamide as a major impurity in the sulfacetamide eye drops. In this study, the magnetic nanoparticles were modified by tetraethyl orthosilicate and 3-methacryloxypropyl trimethoxysilane before imprinting. The magnetic MIPs were prepared through surface molecular imprinting technique, by using Fe3O4 as a magnetic component, sulfanilamide as template molecule, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and 2,2-azobisisobutyronitrile as a radical initiator in acetonitrile/toluene (60:40, v/v) as a porogen. The obtained sorbent was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The selectivity of MIPs for the sulfanilamide impurity absorption was evaluated through adsorption experiments, and the results were compared to the adsorption of impurities by MIPs. Various parameters were optimized including the time, pH, and type of eluent used for the removal of impurities from polymer, concentration of sample, and saturation of polymer. The proposed method was applied to the removal of sulfanilamide from sulfacetamide eye drops. Passing the eye drops through the MIPs led to the quantitative removal of sulfanilamide. Keywords: sulfanilamide; imprinted polymer; sulfacetamide; magnetic nanoparticles; impurity.
degradation product when exposed to light, extreme temperature, or prolonged storage [5]. On storage, aqueous solutions of sodium sulfacetamide undergo hydrolysis into sulfanilamide and sodium acetate. The low solubility of sulfanilamide (0.75 g/100 mL water at 25°C) causes its deposition as needle-like crystals in the ophthalmic solution, which can plausibly cause serious damage to eye tissues [6]. Sulfanilic acid exhibits even greater toxicity than sulfonamides. Therefore, eliminating its presence in drugs is topical [7]. It was reported that pharmaceutical preparations containing sulfonamides or their sodium salts underwent color change as they age, becoming yellow to red-brown, depending on the particular sulfonamide. Various recommendations were provided to eliminate the problem of solution darkening but were not completely successful. The replacement of air by nitrogen in filled containers and the introduction of small percentages of antioxidants in the final sulfacetamide products retard but do not prevent discoloration, particularly on exposure to elevated temperatures, direct sunlight, or prolonged shelf storage [1]. The need for efficient methods of sample cleaning up in medical, food, and environmental analyses is constantly increasing.
1. INTRODUCTION Sulfonamides are importan
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