Stability of Reagents for testing

[DavidP77]

I always have testing reagents left over from year to year and I keep them in a controlled environment. I never know each year what is stable enough to use again next year and what I should reorder though I have some left. Can someone out there with knowledge please advise me on the shelf life in a controlled environment for the following reagents.

R-0871, R-0004, R-0870, R-0013, R-0008, R-0007,R-0009,R-0001, R-0002

Thank you for your help. I have some of all of these left over some from 2 years ago or later but I don't want to use anything old that won't give an accurate test.

[chem geek]

I don't think you are going to get a definitive answer on this, but I'll give you my opinion, for what it's worth. I list below the reagents with descriptions:

2yr R-0001 DPD Reagent #1 (potassium phosphate; sodium phosphate)
1yr R-0002 DPD Reagent #2 (acidic organic amine solution)
2yr R-0003 CC Indicator (potassium iodide)
2yr R-0004 pH Indicator (phenol red)
2yr R-0007 Sodium Thiosulfate
2yr R-0008 TA Indicator (Methyl Red / Bromocresol Green)
3yr R-0009 Sulfuric Acid
2yr R-0013 CYA precipitator (Melamine)
2yr R-0870 DPD Powder (combo of DPD Reagent #1 and #2 plus...)
1yr R-0871 FAS solution (ferrous ammonium sulfate)

My rough take is that the R-0002 and R-0871 solutions are the least stable and should be replaced annually. The R-0870 DPD powder life is dependent on how dry it is kept, but you can usually get 2 years out of it (it starts to look bad even before it becomes unusable). The other indicator solutions, are not unstable, but I would replace them every 2 years to be safe. Inorganic acids last quite a long time so could be kept for 3 years.

I hope others with more experience with shelf life chime in.

Richard