Reagent shelf life

[rjb1211]

How long do the really last?

From the Taylor website:
REAGENT SHELF LIFE

All reagents have a shelf life, whether they are liquids, powders, crystals, tablets, or test-strip pads. If kept dry, powders and crystals are very stable; acids are also long lived. Date of manufacture is not the controlling factor when it comes to shelf life—storage conditions are more important. As with all perishables, reagents are sensitive to environmental influences and will last longer under controlled conditions.

To this end, we recommend:

• Storing reagents at a consistent temperature in the range if 36°–85°F (2°–29°C); extreme temperature fluctuation, say from a refrigerator to a hot car trunk, causes reagents to deteriorate.
• Keeping them out of prolonged direct sunlight. (Note: their brown plastic bottles help protect very light-sensitive reagents.)
• Segregating reagents from containers of treatment chemicals.
• Replacing caps immediately and tightening them carefully so that exposure to air and humidity is limited.
• Avoiding switching bottle caps, placing bottle caps on soiled surfaces, repouring reagents into contaminated containers, or touching test strip pads.

Taylor formulates its reagents to remain effective for at least one year, with only very few exceptions (molybdenum indicator in liquid form is one; after four months old it should be tested against a standard periodically). As a general precaution, replace all reagents more than one year old, or at the beginning of a new testing season.

I keep my test kits inside and out of sunlight. Over the years I have replaced the reagents many time before the bottles were empty just because. I have on occasion done tests with the new bottles and at the same time with the same water sample with the old bottles. The results are always the same. I recently did a DPD test with the stuff that came with my original kit which was purchased in 2005. I got the same results as I did with the newer reagents.

I have rarely gone more than 2 years before replacing the reagents. I am starting to wonder if even at that I am wasting my money.

 

[Newdude]

As with any 'best by' date, the storage conditions can make the results vary widely.

Maybe you notice an issue with one test being way off, maybe you don't and it costs many times more than you saved in the long run.

Anytime i get the same notion, i think of all the money it saved for the 2 years I've had it. Then I happy start over.

 

[Mdragger88]

I have had some discrepancies in the past between fresh & old. Mainly with fc & cya. The others are usually fine pushing 2+ years.
I presume it has alot to do with the fact I use these the most & open the bottles more often. I tend to buy the large bottles for those & refill my small ones.
I know I store them properly but sometimes I do buy from Amazon sellers in bulk & I can’t really vouch for their storage practices. For some that I run through alot I am ok with that.
Tftestkits stuff is always fresh & stored properly so it’s your best bet if you want/need the longest shelf life in my opinion.

 

[Mdragger88]

One other note about storage-
Consider the conditions when the reagents are in transit to you as well.
I try to plan ahead & buy what I need for the season early, before it gets hot out so they aren’t sitting in a hot truck/mail depot somewhere or hanging out in my blazing mailbox all day.
This isn’t always feasible but I do my best.