Design and application of portable mass spectrometers capable of ambient ionization
Abstract
The need for in-situ chemical analysis has increased, especially for compounds detrimental to health or to the environment, and reliability, sensitivity and specificity are crucial in detecting trace levels of these compounds. Mass spectrometry (MS) has proven to be a powerful analytical method in chemical detection, quantification and molecular structure determination due to the sensitivity of analysis and selectivity it affords, but traditionally has been hindered by large instrument size and limitation in sample introduction. The objective of the projects described in this thesis is the development of hand-portable ion trap mass spectrometers capable of sampling ions at atmospheric pressure. Novel introduction methods allow for direct sampling of ions generated at atmospheric pressure and have been shown to accommodate smaller vacuum systems. The instrument that was developed was shown to allow a mass range up to m/z 450 with unit (or better) spectral resolution, limits of detection typically in the low-to-sub ppb range, and tandem mass spectrometric ability. Of most importance, the ability to perform ionization at atmospheric pressure was demonstrated with electropray (ESI) and atmospheric pressure chemical ionization (APCI). Desorption electrospray ionization (DESI) has been recently shown to allow rapid, direct analysis of untreated samples and condensed phases by desorbing neutral molecules from surfaces as secondary ions, and this technique was successfully implemented on a handheld MS system. Several targeted applications were developed for DESI-capable handheld instruments, including analysis of explosives and agricultural chemicals directly from groundwater matrices, detection of illicit drugs and explosives from untreated fabric samples, and detection of compounds important to forensic and veterinary toxicology directly from biological matrices.
Degree
Ph.D.
Advisors
Cooks, Purdue University.
Subject Area
Analytical chemistry
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.