PROBLEM TO BE SOLVED: To provide a pyrroloquinoline quinone (PQQ) potassium salt having a high crystallinity by a method discharging only a small amount of waste liquid and being capable of recrystallization.SOLUTION: A PQQ disodium salt of 5 g is added to ion exchange water, and a sodium hydroxide aqueous solution is added thereto to thereby prepare 300 ml of a solution whose pH is made 6.7, wherein 80 g of potassium chloride is added thereto. At this time, a red solid deposits. Agitation is carried out at room temperature for 16 hours. A crystal is recovered by suction filtration, and is dried under reduced pressure at room temperature for 16 hours. As a result, a crystal of a PQQ tripotassium salt is produced in a yield of 95 mol%.COPYRIGHT: (C)2012,JPO&INPIT【課題】廃液量の少なく再結晶可能な方法により、結晶性の高いピロロキノリンキノン(PQQ)カリウム塩の提供。【解決手段】PQQジナトリウム塩5gをイオン交換水に加え、水酸化ナトリウム水溶液を加えてpHを6.7にした溶液300ml用意した。ここに塩化カリウムを80g添加した。この時、赤色固体が析出した。室温下で16時間攪拌した。吸引ろ過で結晶を回収し、室温下で16時間の減圧乾燥を行った。その結果、PQQトリカリウム塩の結晶を収率95mol%で製造する方法。【選択図】なし
