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Re: Reagent expiration date (was APD vV4 #205
You are probably right, that old/decomposed reagents are usually at the
root of the test kit inaccuracy problem.
What I wonder is WHY the manufacturers, who know how long their reagents
are usable, don't put an expiration date on their kits? It would be
much better, in the commercial sense, if a few LFS returned old kits
because they are past their expiration date, then have the consumer drop
that brand entirely, because of bad results.
The old saw -- shelf life depends on storage conditions -- is true, but
an expiration date based on room temperature storage would go a long way
toward remedying the situation.
In the "good old days" a bad kit might have turned off a single
customer. Now, with Internet communication, it's hundreds of them that
won't touch that brand!
> Seems like a lot of people are coming down on Red Sea CO2 test kits > for
> generally useless results. I don't mean to jump to the company's > defense,but the problem might be due to the age of the kits (reagents) and not to
> the kits themselves. Some chemical reagents used in test kits have a
> definate "shelf life" and beyond that you can't depend upon them for
> accurate readings.
> The people who have had bad luck with Red Sea kits might just have lucked
> into a bunch of old test kits which had been sitting on dealers shelves.
> I have a whole raft of LaMotte and Hach test kits, considered by most of us
> as being among the most accurate a hobbyist can buy and I have also run into
> problems with expired reagents, so the problem is not limited to Red Sea. It
> pays to replace your reagents on a regular basis (another reason to buy a
> quality kit in the first place - cheap ones rarely have reagent replacements
> available separately).