Revellers are being warned to be vigilant against the threat of drink-spiking as the biggest party weekend of the year approaches - but a scientific breakthrough could give police a new weapon in fighting date rape.

Revellers are being warned to be vigilant against the threat of drink-spiking as the biggest party weekend of the year approaches - but a scientific breakthrough could give police a new weapon in fighting date rape.

A 22-year-old student, now at UEA in Norwich, has developed a method that could help detectives pinpoint the time at which mind-altering drugs were dropped into a person's drink. This would make it easier for officers to investigate a crime which is traditionally difficult to solve.

Meanwhile police are warning women that New Year celebrations bring with them an increased threat and has issued advice on how to avoid falling victim.

Sgt Howard Olby of Norfolk police said: “We are not trying to scare people. We simply want to ensure people are aware of the possible dangers whilst out at night. You may see us putting stickers on unattended drinks to reinforce this message over the festive period.”

Hilary Bathgate received a first in her BSc forensic science course at the University of Derby for her revolutionary work in the area and is now studying for a doctorate at UEA.

Her research involved tests on drinks spiked with the date rape drug GHB. The drinks tested were a glass of wine, vodka and Coke, juice drink J20, and a Bacardi Breezer.

By monitoring how the drug degrades in the drink it is possible to identify when the drink was spiked, within a time-frame of two hours.

Ms Bathgate said: “The key development has been being able to help find the time-frame for when a drink may have been spiked, using the degradation process.

“The type of alcohol served also plays a part, with the drug degrading more rapidly in certain drinks, such as white wine in comparison to non-alcoholic drinks such as J20.”

The rate of degradation is also faster at higher temperatures, she said. “If anyone who feels they have had their drink spiked is able to retain even a sample of the spiked drink for analysis, the equation could be used by forensic scientists to help indicate the time frame for when the drink was spiked, using this chemical formula approach.”

The symptoms of these drugs vary but victims report blurred vision and temporary memory loss. The effects can start as quickly as 15 minutes after consumption and can be so severe that victims forget everything that happens.

Drink spiking is illegal, even if an attack has not been carried out. It can result in a maximum of ten years in prison and, for more serious offences, the sentence can be higher.

Women are advised to keep their drink with them at all times, keep and eye on friends' drinks, never accept a drink from anybody they do not know and, if going on a date with a stranger, always tell friends or family where they are going and when they will be back.

Mr Olby said: “Don't be scared by our message: reported cases are very rare, but being aware of the dangers is being ahead of the game. Enjoy your Christmas and have a safe time with friends and family.”