Air bubbles accumulating on the underside of the membrane concerned are the single largest source of problems in Vertical Diffusion Cell testing. For this reason it is essential that the receptor medium used to bathe the membrane is degassed prior to use if air bubbles, and hence impaired diffusion, are not to take place.
The Vacuum Deraeration Apparatus Model VDA is an inexpensive unit that has been designed to oviate this problem. USP Chapter <1092> suggests an oxygen concentration of less than 6 ppm as being effective as a marker for adequate deaeration of the dissoution media. The VDA System guarantees to reduce oxygen levels to below 4 ppm.
The VDA operated by heating the receptor media up to 45 degrees C, under vacuum conditions of -90 kPa differential pressure, whilst continuously stirring at speeds in excess of 1000 rpm to produce truly air free media.
For comprehensive product details, specifications and part numbers, please request a copy of our brochure "Quality Solutions for the Testing of Pharmaceuticals".