Analysis of ancient eyed Chinese papers by high-performance liquid chromatography

The paper of the Dunhuang Diamond Sutra-the world's oldest, dated, printed book-is dyed yellow with an extract believed to contain the alkaloid berberine as the principal colorant. Unambiguous identification of the dye used on this unique book is essential for its conservation. We have developed here a simple, rapid, high-performance liquid chromatography method that gives excellent separation of the protoberberine alkaloids and allows the unambiguous detection of berberine in dyes extracted from tiny fragments of ancient papers. Examination of 25 ancient papers contemporary with the Dunhuang Diamond Sutra revealed the presence not only of berberine but also of the previously unsuspected yellow compounds, palmatine and jatrorrhizine.