Silver Nitrate Issues

[michelleewaldron]

I'm training a new examiner and I made a water based silver nitrate solution (30 g Silver nitrate +
1000 ml deionized water) today and it turned everything I dipped it in brown...immediately, even though we were dipping them in near darkness. I've never had that happen before. Has anyone else? My silver nitrate was purchased in 2014 and I keep the crystals in a light tight box, even though I've heard it's fairly stable in crystal form. From what I have read, it has no expiration date in crystal form. I used, DFO, HFE-based ninhydrin, then silver nitrate, which I have done several times in the past (using the same batch of crystals) with success and I did not use any new recipes. Has anyone else had this happen? Are the crystals just bad? Thanks!