(1999; 168 pages) [Spanish]
6.6 Period of use
Chemical reference substances do not carry an "expiry date" in the conventional sense. To avoid the unnecessary discarding of satisfactory substances, a mechanism for general control of the batch of a chemical reference substance may be used by the issuing body. If the issuing body applies stability considerations and a monitoring procedure based on its experience to its collection, this should guarantee the user of the acceptability of the chemical reference substance for its intended use.
If it is considered necessary to specify a beyond-use date, it should be stated on the label and/or on a document accompanying the chemical reference substances. Adequate shipping records should exist to enable contact with the purchaser of a batch for recall or other notification.
The storage and maintenance of unopened containers of the chemical reference substance in accordance with information provided are integral to its suitability of use. To avoid potential doubts concerning the integrity of opened containers, it is suggested that potential users obtain only the quantities of substances necessary for short-term need and obtain fresh stocks (held under controlled and known conditions) when needed. Long-term storage of substances in opened containers is to be avoided. Similarly, efforts should be made to avoid possible degradation, contamination and/or introduction of moisture during the repeated use of a substance.