Direct capture of the alanine ghost in alanine-doped triglycine sulfate crystals

In this report, ghostly ultra-trace amounts of alanine in alanine-doped triglycine sulfate crystal were directly observed by solid-state nuclear magnetic resonance, and the presence of two chemical states in the cation form and neutral form in the doped alanine was revealed. As the result, the crystal structure of alanine-doped triglycine sulfate was determined for the first time. 15 N-labelled l -alanine in TGS crystals was directly observed by solid 15 N-NMR, with two chemical states of alanine doped into GI being reported and a new crystal structure model proposed.