Does DPD go bad?

[Quickstep192]

I have a container of R-0870 that turned purple over the winter.

Will it still give accurate FC results, or is it toast?

 

[Texas Splash]

They can change color, but it doesn't mean it's bad. If it's left-over from last season but was stored indoors in a relatively cool/dry location it should be okay. Much better than the OTO viewer or pool store testing. Ha ha.