Endotoxin reverse-osmosis membranes

The moleciilia dimensions of bacterial endotoxins are too large to pass through reverse osmosis membranes, and therefore the process is permitted by the pharmacopoeias for production of Water for Injection. However, the outlet water from reverse osmosis units can easily become microbiologically contaminated by formations of films or slimes downstream of the membranes. At least two micraterfogical problems may be encountered with reverse osmosis. First, micit iological films may slough off into the water at unpredictable intervals or... 

The presence of endotoxin should be monitored by LAL method in the routine operation. Endotoxin can be removed by means of distillation, reverse osmosis, and/or ultrafiltration. Incomplete separation of mist in distillation, however, and leakage in membrane of reverse osmosis or ultrafiltration cause contamination with endotoxin. After these separation processes, of course, contamination of microbes or growth of microbes causes endotoxin contamination [2,8],... 

In some cases, reverse osmosis is applied, and this removes almost all the particulates and organic materials, as well as microorganisms and endotoxins. Electrodeionization, which combines ion exchange membranes and resins, removes the last traces of dissolved ions from water under influence of a direct electric current. The last stage of the purification is ozone sterilization of water to inactivate residual microorganisms, as ozone is an efficient disinfectant (UV at 254 nm wavelength is then used to break up the spent ozone). The PW generated is then circulated to each point where it is used (point of use POU). 

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