(303e) Lecithin as An Antistatic Agent for Pure API Crystallizations in Organic Solvents

ABSTRACT: Static buildup in the processing train during pure API crystallizations in organic solvents results in costly glass damage to the vessel internals, and presents a potential safety risk of fire or explosion. The propensity of static buildup is directly related to the conductivity of the solvent system, and is especially high for nonpolar organics such as toluene and heptane. Lecithin is a zwitterionic organic surfactant commonly used in the food and pharmaceutical industry. Lecithin has been proposed as an antistatic agent due to its relatively high solubility in nonpolar organic solvents, as well as its charge carrying capabilities when dissolved in solvents. Lecithin has the advantage over other commercial antistatic agents due to its abundant history of routine use in the pharmaceutical industry even in formulations, thereby reducing the regulatory obstacles associated with additives introduced to the pure API. Experimental results show that addition of lecithin at ppm levels is sufficient to increase solution and pure API slurry conductivity to above the threshold conductivity of 1000 pS/m, with a linear relationship between conductivity and lecithin concentration. However, the amount of lecithin required is also related to the surface area of the API solids, and sufficient lecithin must be added to coat the solid surface with approximately monolayer coverage before the excess lecithin is solvated and electrically active in solution. Finally, head to head comparison studies with and without lecithin for 4 API compounds have shown that lecithin does not negatively impact the crystallization process or the physical properties of the API generated.