How to handle Lab reagents after their Expiration date
Most chemicals have individual expiration dates, so it does depend on what chemical you are
dealing with and what methods you are using it for. For example, if you are using a chemical as a
catalyst, indicator, or in a buffered solution, the exact amount likely doesn 't matter as long as
enough of the active compound is there to cause the desired effect. If however, the compound is
being used as a standard, a titrant, or a reagent in a quantitative analysis, then it might matter a lot.
Look for an expiration date on the chemical’s container or read the accompanying SDS sheet for
stability and storage information, you can usually find needed information there.
Some chemical compounds are time sensitive and have storage condition, whereas others just don 't
go bad at all ever. In general, it is good lab practice to never use chemicals which are older than 5
One should know the chemical management procedures methods used by other laboratories out
there in regards to assign expiration dates to chemicals that were purchased and suppliers did not
state expiration date.
Some manufacturer suggests that for solid chemicals 5 years expiration if manufacturing date is
known and for most liquids 12-18 months expiration also if manufacturing date is known.
If the supplier / manufacturer does not provide an expiration date, for salts we would assign an
expiry period of 5 years for unopened material, 2 years once opened. If you are ordering very
expensive reagents, solids or liquids you might want to insist for retest dates, rather than expiration
dates, if you have the capability to perform functional testing that for organic solvents; IPA, ethanol,
acetonitrile, 2 years unopened and 1 year once opened. There are exceptions though, such as
concentrated acids which would have an expiry of 5 years.
If the manufacturer suggests an expiry date, that date should be followed. The FDA expects an
assessment to be performed for purchased laboratory reagents without expiry date indicated by the
manufacturer. For example, literature review of that specific chemical 's or chemical family 's stability
may be acceptable to determine an appropriate "use by" or expiry date.
Taking in consideration a wide range of applications, the expiration date of a chemical solution
should be established on the basis of their specific use. Some solutions may be too old for one
analytical application, but still suitable for another. For example, a sodium hydroxide solution used
to standardize hydrochloric acid solutions may have reached its expiration date for this type of
application, but it would still be suitable to adjust pH of acids prior to disposal, a less critical
application. In this context, laboratories should establish their own internal standard operating
procedures (SOPs) for the re-placement of chemical solutions after a specific period of time. An
expiration date should be assigned to each type of chemical solutions, i.e. acids, bases, complexing,
argentometric, reducing, oxidising, salts, mixture of sol-vents, etc. For most reagents, with the
exception of those with a manufacturer-specified expiration date, a colour code system may be also
implemented to better identify expiration dates. Chemical solutions are used for a wide variety of
applications. Users should assess a chemical solution for its actual expiration date based on the
application for which the chemical or reagent is being used, taking into consideration the time spend
on preparation and the associated costs, as a policy to improve laboratory performance. In this
context, there is no information in the literature regarding expiration dating of chemical solutions
used in analytical laboratories.
Use of expired chemicals depends on what chemicals you are referring to and what they will be used
for. Some chemicals are very stable and others unstable and very reactive. Check the SDS sheets
and get information on each specific chemical. Silica sand for instance will last virtually forever.
Derivatizing agents are very reactive and if that old need to be disposed of. Ethers can form
peroxides on prolonged exposure to air which can become a potential fire/explosion hazard,
especially when the ether is evaporated and the peroxides concentrate. Always wear appropriate
PPE; gloves, eyes, skin protection when handling chemicals and use proper ventilation! Chlorinated
solvents can slowly decompose and produce phosgene, a deadly poisonous gas. Open chlorinated
solvents in a properly functioning fume hood. Many chemicals are hygroscopic and pick up moisture
over time. In some cases, they can be dried and made potentially usable. If the chemicals are
standards by all means purchase fresh. If they appear usable, they could be tested to determine
their purity or fitness for use but if the chemicals are inexpensive it would probably just be a lot
easier to dispose of them and order new if needed. We should all do our part to help safeguard the
environment. Be sure to check with your state and federal regulations regarding proper disposal of
the old chemicals.