reagents

[tancho]

We have got a customer audit and <e have received the following
observation:

-> When we buy a reagent we take over the expiry period even when we
have opened it.

Now is my question: -> reagent with an expit
y period of 1 year -> After opening expiry period becomes 6 months ?
Are there rules for or based on experiance or stability studies?

fore some reagents of Merck there is no expiry date of retest date
mentioned, what with these reagents ?

Thx

[Bob M]

Expiry dates are highly questionable I puchased some AR Pot phosphate
for almost nothing be cause it had passed expiry date of five years.
My scientific knowledge suggests that this material would be stable
for a few hundred million years if adequately stored. Also I still
have some reagents on hand which I purchased over forty years ago.

If in doubt check the reagent on the test you are going to use it for
does it give the correct reaction etc.
I have also seen reagents well within their supposed shelflife that
have deteriorated to the point of being useless.
Dont assume any thing check it.

Bob M
www.molab.co.nz

[Samite Alchemist]

Hi,

Must separate two issues:

1. When is a reagent no good?

2. When will an auditor give your lab a deficiency?

Question 1 can be hard to determine with certainty. Depends on type
of reagent, how stored, whether opened or unopened, etc.

Question 2 is based simply on the manufacturer's expiration date. If
the manufacturer gives different expiries for unopened vs opened
bottles, use them. Otherwise the single expiry counts no matter how
it has been stored. This system is easy to enforce, but not
sufficient for good lab practice.

Stephen the Samite Alchemist

We all know that reagents sometimes fail before the expiry. That is
why your lab's QA program must have positive as well as negative
checks. My specialty is metals analysis, so I am usually concerned
with stock standard solutions. If the label says 1000 mg/L, but
precipitation leaves only 900 mg/L in solution, my results will be
off. So, an independent check is required after each daily
calibration. Use another stock solution, preferably from a different
vendor, and verify recovery with specified limits. Without such
checks, the lab could be generating junk rather than data.

[analytical chemistry]

Hi,

it is quite obvious that stability of prepared solutions / reagents
has to be confirmed by the lab in order to use them - if not "freshly
prepared", i.e. immediately.

However the issue is regularly brought up by GMP/GLP auditors
regarding commercial chemicals/solvents/reagents

the internal SOP should define such a policy.

I would be glad to discuss the issue, as we have to write this SOP
too ...

A.Nezlin

Post by Samite Alchemist
Hi,
1. When is a reagent no good?
2. When will an auditor give your lab a deficiency?
Question 1 can be hard to determine with certainty. Depends on type
of reagent, how stored, whether opened or unopened, etc.
Question 2 is based simply on the manufacturer's expiration date. If
the manufacturer gives different expiries for unopened vs opened
bottles, use them. Otherwise the single expiry counts no matter how
it has been stored. This system is easy to enforce, but not
sufficient for good lab practice.
Stephen the Samite Alchemist
We all know that reagents sometimes fail before the expiry. That is
why your lab's QA program must have positive as well as negative
checks. My specialty is metals analysis, so I am usually concerned
with stock standard solutions. If the label says 1000 mg/L, but
precipitation leaves only 900 mg/L in solution, my results will be
off. So, an independent check is required after each daily
calibration. Use another stock solution, preferably from a different
vendor, and verify recovery with specified limits. Without such
checks, the lab could be generating junk rather than data.

[Bob M]

Further comment
In most cases expiry dates are at best only a guide line.

If there is any doubt recertify your reagent for its particular
application this usually involves your particular application analysis
with a blank and a spiked sample.
And/Or assay your reagent Stick a label on the bottle with your assays
and dates.
Keep your results for these tests on record for the inspectors as
these tests are in fact a reagent recertification.
Some reagents eg titanous chloride in effect require recertification
every time they are used.

Bob M

[Bob M]

Further comment
In most cases expiry dates are at best only a guide line.

If there is any doubt recertify your reagent for its particular
application this usually involves your particular application analysis
with a blank and a spiked sample.
And/Or assay your reagent Stick a label on the bottle with your assays
and dates.
Keep your results for these tests on record for the inspectors as
these tests are in fact a reagent recertification.
Some reagents eg titanous chloride in effect require recertification
every time they are used.

Bob M