Buffering Solutions

Normally the media makeup is defined in the individual monograph or SOP of a particular product. If not, it is normally distilled water. Buffers work best close to their pKa.

The pH of distilled water can vary between about 6 and 7.2. This may cause some small variations when transferring methods from different laboratories. If pH change is required then this is possible with baskets but other methods such as the USP III or USP IV are more suitable. For some products the absorbencies will vary with pH so multiple standards will have to be made.