You can use your QC documentation to validate the powders.  If you can
demonstrate that you check the quality at each time of use, and you document
it, you can keep using this powders.  You must have a standard operating
procedure that addresses this issues and what you would do in the event of a
failure.  For example, your stain doesn't work. Then, this issue will have
to be documented in your QC form and a corrective action must be generated,
documented, and implemented.
On the other hand, if the powders are not very pricy and you can get smaller
vials that will last you less time, or basically you used them up before
they expire, that will be a more kosher solution to the case.
Good luck, 
Ana Hooker, MT (ASCP)
QC/QA Specialist
Anatomic Pathology
ARUP Laboratories, Salt Lake City, UT

	----------
	From:  Marlene F. LEFEBVRE [SMTP:marlene@arc.ab.ca]
	Sent:  Tuesday, March 21, 2000 12:59 PM
	To:  HistoNet@pathology.swmed.edu
	Subject:  Expiry dates

	Dear Friends. We are attempting to become GLP compliant, and was
wondering
	how others handled expiry dates on the dry powder biological stains
which
	in most part are very stable.  Help would be appreciated. Thanks
Marlene