Twenty-one out of 55 bottles of vintage Scotch whiskies tested at a specialist laboratory have been found to be fake.

The research was conducted at the Scottish Universities Environmental Research Centre (SUERC), based in East Kilbride which is home to one of the UK’s four Radiocarbon Accelerator Units. The lab used advanced radiocarbon dating techniques to forensically test and analyse a range of different whiskies. The analysis, which took more than 9 months to complete, measured residual concentrations of a radioactive isotope of carbon present in the alcohol contained in each bottle in order to establish the ages of the whiskies.

The samples had been sent for analysis by whisky broker Rare Whisky 101 (RW101) on the back of growing concern surround the proliferation of fake whisky in the secondary market.T he bottles had been selected at random from auctions, private collections and retailers.

Of particular note are three rare whisky bottles identified as fakes this included an Ardbeg 1885, which had been acquired from a private owner, Thorne’s Heritage early 20th Century blended whisky purchased from an auctioneer and a bottle of Ardbeg purported to be bottled in 1960’s bought from a retailers.

RW101 said a total of 10 single malts purporting to be from 1900 or earlier were found not to be genuine.

The company said that if tests had proven all 21 bottles to be genuine, collectively they could have been valued at about £635,000. Individual bottles could have fetched anything from £2,500 for the lowest value bottle right up to an estimated £150,000 for the oldest, most valuable bottle.

Professor Gordon Cook, head of the SUERC Radiocarbon Laboratory said: ‘We have had significant help from the major distillers who provided whisky samples of known age that allowed us to start this work.

‘However, it has been our collaboration with Rare Whisky 101 and their provision of really old and rare whiskies that has allowed us to really push this work forward to what we consider to be the Gold Standard technique for identifying the age of a whisky.

‘It is disappointing to see the large percentage of vintage whiskies that turn out to be fake. However, we have developed a very powerful technique to beat the fraudsters and I’d advise anyone thinking about selling what they consider to be an early product to have it analysed.

‘Recently, we have analysed four bottles of early whisky (including a rye whisky from the USA), purported to have been distilled between the mid-19th to the early 20th century, for members of the general public. Of these, three were genuine, so there are really old and rare whiskies in existence.’

The process through which these whiskies have been dated is based on the evolving science of identifying levels of radiocarbon (or C-14) within the liquid. Carbon-14 is that element’s only radioactive isotope and every piece of organic material. Its relatively slow rate of radioactive decay means it has a half-life of 5,370 years. In other words it takes that long for half of it to be gone. Measuring how much Carbon-14 remains in a sample gives an accurate indication of how old it is.