BioEd Online

Nervous consumers who are addicted to the taste of coffee but desperate to cut down on their caffeine will welcome the development on offer from a team of US chemists: a molecule, extracted from llamas, that can easily detect caffeine in a hot or cold drink.

The molecule should be easily utilized, say the team, so that the reaction with caffeine triggers a simple colour-change on a dipstick. Then drinkers could check that their friendly barista really has given them the decaf they ordered.

The research team, led by Jack Ladenson of Washington University School of Medicine in St Louis, Missouri, aims to produce just such a simple test, so users can check that their drinks are jitter-free in the home, at a restaurant or even in the street. Existing methods to detect caffeine require bulky chemical equipment and are therefore confined to the lab.

"The goal is to make it user-friendly," says team member Dan Crimmins. "It won't be a sophisticated device; it would be something like a home pregnancy test."

Leave it to llamas

To find a molecule that would stick to caffeine, the researchers went looking for antibodies that bind to this chemical drug.

Antibodies in most animals are destroyed by high temperatures, making them useless for testing hot drinks such as coffee. But for some reason, the antibodies produced by llamas and camels have a more robust chemical makeup that means they can still do their job at temperatures up to 90 ºC.

So Ladenson's team injected these animals with caffeine to encourage them to produce antibodies against the drug. They then extracted the antibodies and tested their ability to spot caffeine in coffee, cola and decaf coffee. As they report in the journal Analytical Chemistry¹, the test was as effective as previous lab-based methods.

Jitter test

Although described as the world's most popular psychoactive drug for its alertness-boosting powers, many people dislike caffeine's side effects, which can include insomnia, paranoia and high blood pressure.

It's hard to taste the difference between regular and decaffeinated coffees, so it can be easy to accidentally quaff a jitter-inducing version. "There have been several news reports of mix-ups at particular coffee houses," says Crimmins.

The test will need to discriminate between the 80-280 milligrams of caffeine in a regular cup of coffee, and the 5 milligrams typically found in a cup of decaf. The test could also be used on soft drinks and liquid medications such as decongestants to see whether they contain shots of caffeine.

All of this, of course, will be of little consequence for those who view caffeine as one of life's essentials. Indeed, one might suggest that some people would be horrified at the idea of going without it. "Yes, I know," laughs Crimmins. "I have my coffee right in front of me as we speak."

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