Paragraph 2 Reagents and Apparatus
Unless otherwise specified in the method of analysis concerned, all reagents must be analytically pure. The purity of the reagents, especially when determining trace elements, must be checked by a blank test. Depending upon the results obtained, further purification of the reagents may be required.
Where any operation involves preparation of solutions, dilution, rinsing or washing, as part of a method of analysis, water must be used unless the specification of the method indicates otherwise.
Water should, in the absence of good reason to the contrary, be demineralized or distilled. Where indicated in the method of analysis concerned it must be subjected to special purification procedures.
All instruments or apparatus used must be clean, especially when very small amounts of substances have to be determined.