Date: Thu, 13 Aug 2009 13:03:31 -0400
Reply-To: "Harry J. Elston" <helston**At_Symbol_Here**FGI.NET>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: "Harry J. Elston" <helston**At_Symbol_Here**FGI.NET>
Subject: Re: Assigning expiration dates
Comments: To: "Dr. Jay A. Young"
Two notable exceptions to Jay's wisdom:

1.  There may be regulations regarding prepared standards in certified laboratories, such as ones that perform organic or inorganic analysis for drinking water.  I would first go to the EPA Laboratory Certification Manual (now in it's 5th edition) for guidance there.  I believe it's 6 mo or a 1 year, but don't quote me on that.  I do know that auditors will give you the fish-eye for having calibration standards older than 6 months for organics standards and 1 year for inorganic standards, and may even make these a "finding" on an audit.

2.  Prepared radiological standards are usually kept until they are no longer useful because of decay problems.  Depending on original source strength, isotopic half-life and counting instrumentation, that could mean days, years or decades.

Other concerns that you need to be aware of are cross-contamination problems (i.e. sticking a pipette contaminated with another standard into the bottle) and concentration issues (i.e. leaving the cap loose).  Both of these are training issues.

-----Original Message-----
>From: "Dr. Jay A. Young" 
>Sent: Aug 13, 2009 10:04 AM
>To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
>Subject: Re: [DCHAS-L] Assigning expiration dates
>To establish an expiration date for any locally prepared reagent or reagent 
>mixture requires a reasonably thorough knowledge of the properties of each 
>of the components that are involved--all of which would of course include 
>the supplier's recommended expiration date for one or more of the 
>components--but that information would NOT be the sole factor.
>In practice, the above required information often is not always available. 
>In such cases, one simply has to fly by one's pants (so to speak).  I 
>recommend setting a brief arbitrary period of utility, say 3 (or perhaps 6) 
>months from the date of preparation but in no case greater than 6 months.
>Then, if the date selection is, say, 5 months, test the stuff at the end of 
>4 or 4.5 months and if it is still OK, then, arbitrarily extend the 
>expiration date to, say 7 months and so on.
>Thus, test it again at 6.5 months and if OK extend to 8 months.  Etc.
>But in no case for a standard would I use it as a standard after one year. 
>And of course, in some instances, it would be necessary to store a standard 
>under controlled conditions for the entire period of its valid use.
>Jay Young
>----- Original Message ----- 
>From: "Roger Brauninger" 
>Sent: Wednesday, August 12, 2009 3:58 PM
>Subject: [DCHAS-L] Assigning expiration dates
>>I was wondering if there is a rule of thumb for assigning expiration dates
>> of working stocks, etc.  For example: An analytic method specifies that a
>> given standards solution (A) is good for one year (expires a one year 
>> after
>> preparation).  "A" is made from a commercially prepared standard, which 
>> has
>> its own expiration date.  In the situation where the expiration date on 
>> the
>> commercial material is one month after the current date and a solution of
>> "A" is made up from it, is the expiration date still one year after the 
>> date
>> of "A's'" preparation or much it be restricted to the expiration date of 
>> the
>> commercial standard. In this case one month.
>> To add to the discussion the Code of Federal Regulations, 40CFR, Section
>> 58.113, (c ) states, "Where any of the components of the test or control
>> article carrier mixture has an expiration date, that date shall be clearly
>> shown on the container.  If more than one component has an expiration 
>> date,
>> the earliest date shall be shown."
>> This is a difficult issue to come up with a unilateral approach because we
>> have seen instances where the exact same neat materials (Reference 
>> Materials
>> for example but it could be any chemical for that matter) which are sold 
>> by
>> different manufacturers have had different expiration dates assigned to
>> them.  So there is variability even with the neats.  The GLP approach is
>> certainly valid for a number of materials however, for example 
>> radioisotopes
>> but assigning an expiration date also depends on other properties of the
>> materials, for example whether they react or degrade (organics for 
>> example),
>> or do not (most metals).  Most producers say that it is appropriate to
>> re-qualify a material.   However it all boils down to having knowledge of
>> the materials at hand and the purpose for which they are used.
>> Thoughts?
>> Roger M. Brauninger
>> BioSafety Program Manager
>> 5301 Buckeystown Pike
>> Frederick, Maryland 20895
>> Direct line: (301) 644-3233      Fax: (301) 662-2974
>> Email: Rbrauninger**At_Symbol_Here**
>> The information contained in this transmission may be confidential
>> information intended only for the use of the individual or entity named
>> above. If the reader of this message is not the intended recipient, you 
>> are
>> hereby notified that any dissemination, distribution or copying of this
>> communication is strictly prohibited. If you have received this
>> communication in error, please notify us immediately by telephone and 
>> delete
>> the original message. Thank you.

Harry J. Elston, Ph.D., CIH
Midwest Chemical Safety, LLC

Editor, Journal of Chemical Health & Safety

Nationalized health care:  All the efficiency of FEMA with all
the compassion of the IRS

Previous post   |  Top of Page   |   Next post

The content of this page reflects the personal opinion(s) of the author(s) only, not the American Chemical Society, ILPI, Safety Emporium, or any other party. Use of any information on this page is at the reader's own risk. Unauthorized reproduction of these materials is prohibited. Send questions/comments about the archive to
The maintenance and hosting of the DCHAS-L archive is provided through the generous support of Safety Emporium.