FWIW, just sharing my recent experience after starting up testing again.
Have a 10-15-year-old TF-100 test kit. Stored in the basement at very constant room temperature in a closet all the time, and there's no sign of degradation on any of the reagents. Only the the DPD powder has turned grey, but it seems to be working just fine.
The R-0871 titrating reagent is completely clear, no sign of yellowish as I have read in other threads being the sign to look fore when getting old.
However, my FC results from FAS-DPD seemed too high compared to DPD tablets.
I ordered a new set of FAS-DPD reagents, and conclusion now is that my old reagents show about 50% too high FC value.
Have a 10-15-year-old TF-100 test kit. Stored in the basement at very constant room temperature in a closet all the time, and there's no sign of degradation on any of the reagents. Only the the DPD powder has turned grey, but it seems to be working just fine.
The R-0871 titrating reagent is completely clear, no sign of yellowish as I have read in other threads being the sign to look fore when getting old.
However, my FC results from FAS-DPD seemed too high compared to DPD tablets.
I ordered a new set of FAS-DPD reagents, and conclusion now is that my old reagents show about 50% too high FC value.
