Water R1

Prepared from distilled water by multiple distillation. Remove carbon dioxide by boiling for at least 15 min before use in a boiling flask of fused silica or borosilicate glass and cool. Any other suitable method may be used. The boiling flask has been already used for the test or has been filled with water and kept in an autoclave at 121° for at least 1 h prior to first use. When tested immediately before use, water R1 is neutral to methyl red solution, i.e. it shall produce an orange-red (not a violet-red or yellow) colour corresponding to pH 5.5 ± 0.1 when 0.05 mL of methyl red solution is added to 50 mL of the water to be examined.

Conductivity Maximum 1 µS⋅cm^-1, determined at 25° by an in-line conductivity meter (see Purified water (0008)).