A lighter approach to spectroscopy

US researchers at the University of Rochester have developed a technique that in 60 seconds or less measures multiple chemicals in body fluids, using a laser, white light, and a reflective tube.

The method tests urine and blood serum for common chemicals important to monitoring and treatment of diabetes and cardiovascular, kidney, urinary and other diseases, and lends itself to the development of fast batch testing in hospitals and other clinical settings.

The researchers used low-refractive-index tubes instead of cuvettes or other bulky containers for holding biological specimens. To get more information from the fluids, they used white light from a standard light bulb along with the laser.

The method improves on Raman spectroscopy, a laser technique for finding chemicals that overlap and mix in fluid. However, the Raman signal is notoriously weak and not the first choice for use in biofluids.

The researchers injected fluid samples into a thin transparent tube specially made to contain the light, and the tube's long path length of interaction let the scientists collect more Raman scattering. They did get the stronger signal they were looking for, but the increase threw off measurements when samples of urine or blood serum varied in colour.