PNNL

Abstract

An atmospheric flow tube (AFT) provides extended ion-molecule reaction times of 2-3 seconds compared to milliseconds in typical mass spectrometers. This results in several orders of magnitude enhanced sensitivity allowing for vapor detection at the parts-per-quadrillion levels when an AFT is coupled to a mass spectrometer (MS). The goal of this project was to demonstrate the feasibility of integrating an AFT ionization source to a more portable ion mobility spectrometer (IMS). This project was successful in integrating AFT to IMS, as shown in Figure ES.1. The PNNL team demonstrated measurable ion signal from an AFT-IMS with a Faraday plate detector. Reasonable ion signals were detectable at low flow rates approaching 1 m/s. This is close to the flow rates used with the AFT-MS, which has demonstrated parts-per-quadrillion vapor detection. Vapor detection enables non-contact detection of a variety of illicit substances for various applications including cargo screening, mail sorting facilities, and checkpoints. With further improvements to enhance detection, AFT-IMS has the potential to allow ultra-trace vapor detection in a more portable device.