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 ====== Preparing NMR samples ====== ====== Preparing NMR samples ======
-To prepare NMR samples inside a glovebox, NMR tubes with a //Young-type// PTFE cap are recommended. They provide long-lasting leak-tightness and remain tight under vacuum. This is important for bringing samples back into the glovebox through the antechamber.+To prepare NMR samples inside a glovebox, NMR tubes with a //Young//-type PTFE cap are recommended ({{ref>tube}}). They provide long-lasting leak-tightness and remain tight under vacuum. This is important for bringing samples back into the glovebox through the antechamber. 
 + 
 +<figure center|tube> 
 +{{:analytik:nmr:signal-2026-04-07-161528_003.jpeg?direct&200 |title}} 
 +<caption>A NMR tube with a //Young//-type PTFE cap.</caption> 
 +</figure> 
 + 
 +As with all PTFE caps and taps, they are properly tightened when a white ring is visible inside the glass ({{ref>sealing}}). Tightening it further will not lead to a better seal, but rather increase the risk of damaging the glass. Also, keep the sealing surfaces clean of any powder to ensure proper sealing. 
 + 
 +<figure center|sealing> 
 +{{:analytik:nmr:unbenannt.png |title}} 
 +<caption>This is a close-up view of the sealing area. A white ring inside the glass indicates proper sealing.</caption> 
 +</figure> 
 + 
 +===== NMR solvents ===== 
 +The standard NMR solvent is deuterated chloroform. However, it is often unusable in organometallic chemistry because of its acidic proton. Therefore, deuterated benzene is the preferred NMR solvent in most cases. When more polar or donating solvents are needed, deuterated dichloromethane and THF can be used instead. These solvents are rather expensive, though, and should only be used when necessary. Since benzene freezes at 0 °C, deuterated toluene can be used as an alternative solvent for experiments conducted at lower temperatures.