New NIST Raman spectrometry standard for handheld chemical detectors makes different instruments equal in output

Gaithersburg, MD-The recent publication of a new standard for Raman spectrometers—a culmination of years of research at the National Institute of Standards and Technology (NIST)—provides confidence that results from handheld chemical detectors can be compared directly. These detectors are used by emergency responders to check for the presence of explosives or toxic chemicals; in addition, quality-control managers in the pharmaceutical industry use them to verify the identity of chemicals going into their production lines.

The new standard, published recently by ASTM International (Conshohocken, PA), a standards-development organization, is intended as a guide to correct the output from different handheld Raman spectrometers, so that different instruments produce the same result for the same sample. Ordinarily, Raman spectrometers from different manufacturers can produce signals with different peak intensities; these differences can be confusing, particularly if first responders from different agencies use different instruments and get differing results on an unknown sample in the field.

"Our goal is that people get the same answer for the same sample on any machine," says NIST chemist Steven Choquette.

His team developed a series of NIST standard reference materials (SRMs) that are used to correct Raman systems with differing excitation lasers. These standards enable the correction of the differences in peak intensities reported for the same sample by different Raman spectrometers. They then continued to work with spectrometer manufacturers to develop an industry consensus standard to enable comparisons among Raman spectrometers.