When it comes to detectors for dangerous chemicals, toxins, or nefarious germs, smaller and faster is better. But size and speed must still allow for accuracy, especially when measurements by different instruments must give the same result.
The recent publication of a new standard for Raman spectrometers provides confidence that results from handheld chemical detectors can be compared, apples-to-apples.
Emergency responders use such detectors to check for the presence of explosives or toxic chemicals that threaten public safety. Quality control managers in the pharmaceutical industry use them to verify the identity of chemicals going into production lines.
Christopher Neary of NIST demonstrates the use of a handheld Raman spectrometer to identify an unknown sample.
The new spectrometer standard, published recently by ASTM International, is a culmination of years of research at the US National Institute of Standards and Technology (NIST).
The standard is intended as a guide to correct the differences in peak intensities reported for the same sample by different Raman spectrometers.
Raman spectrometers identify chemicals by shining laser light on a sample and detecting the very small changes in the wavelength of that light as it is re-emitted from the sample.
However, 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.
“Our goal is that people get the same answer for the same sample on any machine,” says NIST chemist Steven Choquette, whose team developed a series of NIST Standard Reference Materials to correct Raman systems with differing excitation lasers.
Read more about the newly published Standard Guide for Relative Intensity Correction of Raman Spectrometers (designated as E2911-13).