With the Supplement 6.3 to the European Pharmacopoeia, some changes with regard to water for pharmaceutical use came into force in 2009. They affect water for injection (WFI), highly purified water (HPW) as well as purified water (PW).
Basically, the changes are the same for all three water qualities. WFI is an exception; in the section on sterilised water for injection, the tests for oxidizable substances and ammonium are also concerned. For both testing procedures, there is now a distinction between containers larger or smaller than 50 ml.
What is identical for all three water qualities is the introduction of the new section on microbiological monitoring. Apart from mentioning the action value of 100 CFU/ml respectively 10 CFU/100 ml (limits unchanged), exact types of test strains, growth conditions and the agar to be used have been taken over.
The more detailed description of conductivity measurement, too, can be found in all three qualities. With regard to the conductivity cell, there is now a note that the cell constant has to be certified by the supplier and that this has to be calibrated regularly against a certified reference solution or against a conductivity cell with certified cell constant.
However, the most important change is certainly the long-awaited cancellation of the test for heavy metals, since this test point is covered by the conductivity measurement. This also concerns all three water qualities mentioned, with the exception that the test can only be dropped for purified water in case conductivity testing fulfils the requirements on WFI (bulk). This is a further step towards a harmonisation with the American pharmacopoeia (USP).
Dr Robert Eicher
On behalf of the European Compliance Academy (ECA)