ASTM E2677: International Standard on Limit of Detection for Trace Detectors—Explosives, Opioids, and Ozone

摘要

The performance characteristics of explosive and narcotic trace detectors are mission critical to agencies worldwide that are charged with protection of the public, defense for mass transit and infrastructure, illicit drug interdiction, and the safety of first responders. Commercial trace detectors can measure signals from nanogram-size analytes in complex matrices, but even with proper maintenance, detector performance can degrade over time. Sensitive indicators of performance include the limit of detection and the minimum consistently detectable amount (MCDA), which are distinctive for each analyte in each detector for a given set of operating parameters. ASTM Subcommittee E54.01, with help from industry and agency stakeholders, recently approved ASTM E2677-14, Standard Test Method for Determining Limits of Detection in Explosive Trace Detectors. This method allows a well-characterized MCDA to be estimated in accordance with International Organization for Standardization and International Union of Pure and Applied Chemistry (IUPAC) measurement, detection, and uncertainty concepts. Challenges of background interference, response nonlinearity, heteroskedastic behavior, and truncation by signal filters were considered. Data are input into a web-based calculator on a National Institute of Standards and Technology (NIST) cloud server in which data quality is assessed, calculations are performed, and results are returned to the user. This method is gaining use worldwide as a well-documented mechanism to estimate MCDA values and is now being considered by ASTM for a wider audience of users. We describe some of the details of this method and demonstrate two other applications: (1) ozone measurements that were simultaneously collected on two commercial monitors and the NIST Standard Reference Photometer; and (2) trace opioid samples that were measured using a variety of techniques: ion mobility spectrometry, gas chromatography/mass spectrometry, and thermal desorption-direct analysis in real time-quadrupole mass spectrometry. We believe many environmental applications could benefit from such an approach.