# Why does Li get darker in a glove box?

I'm having some issues with lithium getting darker in a glove box. Please see attached photos, Li gets dark overnight.

My sensors for $\ce{H2O}$ and $\ce{O2}$ are showing 0 ppm. I also checked oxygen and moisture contents using chemicals in case sensors were bad, and looks like there is no oxygen and moisture in the glove box. Just to make sure, I also replaced the nitrogen tank with argon (there are some reports in the literature saying Li reacts with nitrogen even at room temperature and gets darker in the presence of trace levels of moisture).

Does anyone had this problem before? Any recommendations would be of great help.

• What chemicals did you use and are they really more sensitive than Li? – Ivan Neretin May 17 '17 at 20:38
• I do not use any chemicals in the glove box at the moment. Li is only exposed to the glove box atmosphere which is argon. Additional details, nothing is transferred from the ante-chamber during the past day. – Dervis May 17 '17 at 21:54
• How pure is the argon? A little moisture or oxygen overnight goes a long way with lithium. I suspect the lithium is catching something below your detection limits. – Oscar Lanzi May 18 '17 at 1:15
• @Dervis I mean, those you've used to check oxygen and moisture contents. What are they? – Ivan Neretin May 18 '17 at 4:00
• Since argon is produced from air by cryogenic fractional distillation, it may still contain traces of nitrogen as also mentioned here. – user45298 Jul 17 '17 at 14:57