New method yields fast results in drug, medical testing

A new technique quickly detects the presence of drugs or monitors certain medical conditions using only a single drop of blood or urine, representing a potential tool for clinicians and law enforcement.

Called "slug flow microextraction", the technique works by extracting minute quantities of target molecules contained in specimens of blood, urine or other biological fluids, and then testing the sample with a mass spectrometer, researchers said.

"Testing carried out with the technology takes minutes, whereas conventional laboratory methods take hours or days to yield results and require a complex sequence of steps," said Zheng Ouyang, associate professor in Purdue University's Weldon School of Biomedical Engineering.

The method could be used to detect steroids in urine for drug screening in professional sports and might be combined with a miniature mass spectrometer also being commercialised.

"In the future, parents might be able to test their children's urine for drugs with a simple cartridge they would take to the corner drug store, where a desktop mass spectrometer would provide results in a few minutes," Ouyang noted.

The technique involves drawing a specimen into a glass capillary that also contains the organic solvent ethyl acetate.

Like oil and water, the two fluids are immiscible and an interface is formed between the specimen and the solvent.

"Gently rocking the capillary back and forth several times causes small amounts of target molecules in the biological sample to cross this interface into the solvent side without mixing the two fluids," Ouyang informed.

The overall goal is to use this technology for developing disposable sample cartridges to work with mini mass spectrometry system in clinical and home settings, researchers concluded.

The paper appeared in the research journal Angewandte Chemie International Edition.