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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.

enter image description here

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    $\begingroup$ What chemicals did you use and are they really more sensitive than Li? $\endgroup$
    – Ivan Neretin
    May 17 '17 at 20:38
  • $\begingroup$ 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. $\endgroup$
    – Dervis
    May 17 '17 at 21:54
  • $\begingroup$ 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. $\endgroup$
    – Oscar Lanzi
    May 18 '17 at 1:15
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    $\begingroup$ @Dervis I mean, those you've used to check oxygen and moisture contents. What are they? $\endgroup$
    – Ivan Neretin
    May 18 '17 at 4:00
  • $\begingroup$ Since argon is produced from air by cryogenic fractional distillation, it may still contain traces of nitrogen as also mentioned here. $\endgroup$
    – user45298
    Jul 17 '17 at 14:57
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Lithium can react with nitrogen giving a dark product. https://en.wikipedia.org/wiki/Lithium

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I suspect your sensors provide instantaneous readings, while the surface of the Li represents exposure integrated over time.

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But your glove-box does use Argon and not nitrogen, right? Nonetheless, it's a pretty common even for new glove boxes. We seal all our products and important reagents in secondary tight containers in the glove box just to make sure. Whenever you add something new, at least some contamination will come in and you never know what the guy after you does and how careful he works.

I remember to have prepared a metal carbonyl hydride once using Schlenk-technique. It was bright yellow. We placed it into a glove-box where it turned orange. Although the sensors didn't show anything you could smell sulfur-like compounds. And even in our glove-box, and we only prepare dry, solid-state compounds, the air, that leaves when you open the box smells like selenium and sulfur. There is always some contamination in the air and once this happens your lithium is likely to react with it quite fast and you don't see much on the sensors.

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