PROBLEM TO BE SOLVED: To provide a crystal of very pure and stable PQQ (pyrroloquinoline quinone) sodium salt and a simple method for producing the same.SOLUTION: The pyrroloquinoline quinone disodium salt crystal including three or less molecules of water in a crystal lattice is produced by suspending a trisodium salt of PQQ in water, then adding water-soluble organic solvent to the suspension to reduce the solubility of the PQQ trisodium so that the pH falls in the range between 2 and 5. There is also provided a method of reproducing the crystal by placing broken crystals in an environment of 20-100% humidity for 15 minutes or longer.COPYRIGHT: (C)2013,JPO&INPIT【課題】高純度で安定なPQQ(ピロロキノリンキノン)ナトリウム塩の結晶及びその簡便な製造方法を提供すること。【解決手段】PQQのトリナトリウム塩を水に懸濁させた後、この懸濁液に水溶性有機溶媒を加えPQQのトリナトリウム塩の溶解度を下げ、pHを2~5の範囲に調整することにより製造した、結晶格子内に3分子以下の水を含むピロロキノリンキノンジナトリウム塩結晶および、該結晶が壊れたものを湿度20から100%の環境に15分以上置くことで結晶を再生する方法。【選択図】図1
