Water distiller

Chinese pharmacopoeia 2010 version specifies that WFI is obtained by distillation of purified water. WFI is usually generated by following three distillation methods: 

◎ Single-effect distillation 
◎ Multi-effect distillation

◎ Thermocompression distillation 

Distillation is a process for chemical and microbiological purification of raw water by gas-liquid reform and separation. In the process, water is evaporated, in which produced steam breaks away from water, and unevaporated water flowing to behind is dissolved with solids, non-volatile substances and macromolecular impurities. In the distillation process, low-molecular impurities may be entrained and carried in evaporated steam in the form of water mist or droplets, so it needs separation device to remove tiny water mist and entrained impurities, including endotoxin. Purified steam becomes water for injection after condensation. Distilling method can reduce at least 99.99% of endotoxin content.

Requirements for validation has been improved in Chinese new GMP. In order to meet validation requirements and reduce risk of system, it is recommended that WFI generation equipment is previded with automatic control function, so that control parameters required in validation can be monitored and recorded online. Establishment of automatic control method and system can refer to GAMP (Good Automated Manufacturing Practice).