A new laser-powered chemical analysis technique is so sensitive that it can take dozens of samples from a single strand of hair, distinguishing between the chemical signatures of each.

Existing methods destroy small samples, and don’t give exact time-based measurements. But using the new technique, forensic scientists could turn that strand of hair into hour-by-hour measurements of what someone ate or where they went.

“With a single hair, we’ve shown you can take carbon isotope measurements over time instead of just chopping up the sample and averaging everything,” geochemist Jim Moran of Pacific Northwest National Laboratory, whose team describe the technique April 12 in Rapid Communications in Mass Spectrometry.

Standard chemical analysis involves the use of mass spectrometers, machines that weigh and categorize particles from samples after they’re pulverized. Lasers are are typically too powerful to extract samples, as they burn organic material before it can be properly analyzed.