Original manuscripts of Robert Burns' poetry sell for up to £90,000 ($120,000), predictably attracting forgeries. Analytical chemistry has long provided ways to detect unsophisticated fakes, but now high-resolution mass spectrometry has made it possible to identify forgeries that have previously been too hard to recognize. The same technique could confirm or refute the authenticity of many other historical documents and works of art.

Burns produced a remarkable volume of work in his 37 years, but within a century of his death in 1796 this was overwhelmed by the number of manuscripts purporting to be his, carrying both real Burns poems, as well as works by others. Many of them were produced by Alexander Howland Smith in the 1880s, whose imitations of Burns’ handwriting fooled most of his contemporaries. Smith went to jail for selling his forgeries, but by then many had entered circulation, and still turn up at auctions purporting to be the real thing.

Some fakes have been identified using isotope dating to establish the age of the materials they are made from. However, modern forgers are often onto this. Even Smith, who certainly could not have known about radiocarbon dating, often used blank pages taken from old books to confuse his contemporaries (other times he just dipped his products in tea to give them an aged appearance).

James Newton of the University of Glasgow applied infusion nanospray mass spectrometry to both the paper and inks of confirmed Burns originals, and compared them with works known to come from Smith. The quantities of material required for this are so tiny they do no significant damage to the manuscripts – unlike thin-layer chromatography and liquid chromatography, the traditional techniques used to test ink’s authenticity.

In Scientific Reports, Newton describes how he identified chemicals present in at least some of Burns’ manuscripts and absent from Smith’s forgeries, or vice versa.

The work’s importance extends beyond those willing to pay a small fortune for a famous poet’s handwriting. “Historic documents can have great significance in many respects,” the paper points out. “They can, for example, give insight into the opinions of leading individuals whose influence on society is profound. In some cases they might be of legal importance, underpinning ownership of land or valued property.”

Burns’ work is valued both for his influence on Romantic poetry, and his status among Scots both at home and abroad. Burns nights held on his birthday have become a sort of second Scottish national day. An attempt to estimate the value of Burns’ legacy to the Scottish economy came up with the figure of £157 million ($207 million) per year a decade ago, and while only a small fraction of this is affected by the forgeries, he’s hardly the only figure whose works have been inspired such imitation.