NUS News

Chemistry team develops world’s first fluorescent date-rape drug sensor

Club-goers will soon be able to detect within 30 seconds if their drinks have been spiked, with the world’s first GHB fluorescent sensor developed by NUS researchers. GHB or Gamma-Hydroxybutyric acid is a central nervous system depressant, which has been used in medical settings as a general anaesthetic. Today, it is most commonly used as a date-rape drug, which renders victims incapacitated and vulnerable to sexual assault. The breakthrough method to detect the presence of GHB contributes therefore towards the prevention of drug-facilitated sexual assault.

“We wanted to develop something that would give results within several seconds, so you can check whether it is a safe drink or whether you should stop and think again,” said NUS Chemistry Professor Chang Young-Tae, who supervised the team that discovered the sensor. His team members, also from the NUS Department of Chemistry, were Research Fellow Dr Zhai Duanting, PhD candidate Mr Xu Wang and recent graduate Mr Elton Tan. Their findings were published in the Chemical Communications journal earlier this year.

As GHB is odourless, colourless and slightly salty, it is almost undetectable when mixed in a drink, thus making it desirable to sexual predators. A small amount of between two to four grams of GHB will interfere with the motor and speech control of a person, and may even induce coma-like sleep. GHB takes effect within 15 to 30 minutes, and the effect can last for three to six hours. It is only detectable in a person’s urine six to 12 hours after ingestion.

This sensor, which can detect GHB at concentrations of 10 mg/ml and higher, is a better detector than existing methods because of its high sensitivity, fast response time and technical simplicity. According to Prof Chang, the colorimetric method of testing is not as sensitive as GHB Orange, and the chromatography test is expensive to produce and may take as long as 20 minutes.

When the sensor, GHB Orange, is added to a drink that has been spiked with GHB, the sensor’s fluorescent colour loses its intensity. This loss in intensity is observed as a change from orange to clear if the drink is translucent or light-coloured, or to a colour with a shorter wavelength such as blue or green, depending on how the fluorescent orange colour combines with the drink’s original colour. This change is best observed under green light, but is also observable under other kinds of lighting.

Prof Chang and his team, who are working with product designers and fabricators, intend to come up with a portable detection kit within a year. One of the product scenarios includes that of using a cell phone as a reader since some phones come with a flashlight function that can be used to irradiate the sensor. The team believes that it can market a kit of 10 tests for S$1.

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