Aspirin particle formation by electric-field-assisted release of droplets

An aspirin solution flowing through a needle at () was subjected to an electric field of to generate droplets. The aspirin droplet size distribution generated was measured and is shown to be trimodal with the most significant size, . Deposited droplets and their aspirin crystal relics were also studied by electron microscopy. Immediately after deposition, the droplets were remarkably uniform in size and produced particulate crystals and were considerably more regular in morphology when compared with those formed without using an electric field.     

Enzyme kinetics of kinetic resolution of racemic ibuprofen ester using enzymatic membrane reactor

An ultrafiltration hollow fiber enzymatic membrane reactor was employed to study the kinetics of lipase-catalyzed kinetic resolution of racemic ibuprofen ester. Lipase from Candida rugosa was employed in the hydrolysis reaction both in free form in a batch system and in immobilized form in an enzymatic membrane reactor (EMR). The half life (t_1/2) of immobilized lipase on spongy layer was 105 h at reaction temperature of and 62 h at . This value was 94 h for lipase immobilized on the inner lumen and 45 h for free lipase in batch system at . Excessive substrate was found to inhibit the reaction as an uncompetitive inhibitor. The by-product 2-ethoxyethanol was found to be non-competitive inhibitor to the reaction when it was present in an excess. Michaelis constant (K_m) and maximum reaction rate (V_max) for immobilized lipase were and , respectively; and that for free lipase were and h^-1, respectively.