Modern analytical tools such as mass spectrometers can identify many unknown substances that allow scientists to easily determine whether foods or drugs have changed. However, the cost, size, power consumption and complexity of these devices often prevent their use in limited resource areas. Now, at The Scientific Center, Researchers say they have developed a simple and inexpensive method for identifying samples by seeing how they respond to changes in their environment.
According to the World Health Organization, about 10% of all drugs in low- and middle-income countries are not healthy or counterfeit. As with counterfeit medicines, fake foods can also put consumers at risk of illness or death, in addition to costing the industry billions of dollars a year. William Gruber and his colleagues at the University of California at Riverside wondered whether they could develop a simple, cheap, and reliable test to compare unknown samples with authentic foods and medications. The researchers based their test on "chronoprints," a term they use to describe capture images and how a sample changes over time and time in response to interference – in this case, a sudden temperature change.
The researchers are loading some liquid samples into long parallel channels on a microfluidic chip. They then deposited one end of the chip into liquid nitrogen, creating a temperature gradient that caused the samples to freeze, thaw, separate with components, or change with time and distance from liquid nitrogen. With the USB camera, they were captured videos of how the samples changed, converted these videos to pictures and compared the images using computer programs. The researchers found that identical samples, such as the same brand of cold medicine or extra virgin olive oil, were very similar, while the fancy drugs or olive oil did not. In principle, the method, which is much less expensive than the current approach, can also be used for analysis of dissolved gases or solid samples, the researchers say.
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