Do metabisulfite and sorbate expire?

Its been over a year since I have brewed anything other than rice wine. Im ready to get back into it and I am purchasing my ingredients now. I have some tablets of potassium metabisulfite leftover that are unopened, are they still okay? The sorbate I am most worried about, the bag was opened and sealed with just a chip clip. They were both stored in a dry dark area. Are they okay or should I throw them out and buy more? Money isnt the issue, I prefer not to waste though.