Eric Reese

Interactive Self-Modeling Mixture Analysis of Ion Mobility Spectra:

Ion mobility spectrometry (IMS) has been successfully developed to yield an advanced portable instrument. However, the formation of pure or heterogeneous cluster ions introduces nonlinear variances into the data. Cluster ions may arise from the sample in addition, and competition to the standard anticipated product ions and may deleteriously affect quantitative determinations. The SIMPLISMA (simple-to-use interactive self-modeling mixture analysis) method is demonstrated for detecting and modeling these nonlinear variances in IMS data, which is especially useful when vapor mixtures are encountered. Furthermore, SIMPLISMA may assist in the resolution of overlapping peaks that are characteristic of low-resolution IMS drift tubes. The synergistic combination of IMS and SIMPLISMA is shown for the detection of heterogeneous cluster ions produced from vapor mixtures of 1-pentanol and 1-octanol.

THE ANALYSIS OF METHAMPHETAMINE HYDROCHLORIDE BY THERMAL DESORPTION ION MOBILITY SPECTROMETRY AND SIMPLISMA

Ion mobility spectrometry (IMS) has been successfully developed to yield an advanced portable instrument. Such instruments may detect trace quantities of regulated substances at the crime scene. The atmospheric ion chemistry that occurs within the instrument may hinder the determination of analytes in real-world samples. The use of temperature programming adds an extra dimension to the data that improves the selectivity of the IMS data when chemometric processing is applied. The SIMPLISMA (SIMPLe-to-use-Interactive Self-Modeling Mixture Analysis) method is demonstrated for modeling variances in IMS data that are introduced from the temperature program. Methamphetamine hydrochloride IMS peaks are obscured by chemical interferences that arise from cigarette smoke residue. Cigarette smoke residue is pervasive at crime scenes. The ability of SIMPLISMA to resolve the analyte peaks that correspond to methamphetamine hydrochloride from interfering cigarette smoke has been demonstrated. A reduced mobility of 1.62 cm2V-1s-1 was observed for a methamphetamine hydrochloride monomer. With the IMS drift tube at room temperature, a second peak was observed at 1.24 cm2V-1s-1, which is consistent with a dimer ion. This peak has not been previously reported.

Results of the Air Quality Monitor's Experiment to Measure Volatile Organic Compounds aboard the International Space Station

The Volatile Organic Analyzer (VOA) provided 9 years of information on the trace volatile organic compounds (VOCs) in the atmosphere of the International Space Station (ISS), but it was decommissioned in August 2009. The NASA’s Toxicology Laboratory at Johnson Space Center and others have been evaluating technologies to replace the VOA for several years. One system investigated by the NASA’s Toxicology Laboratory was Sionex’s microAnalyzer™ (later designated the Air Quality Monitor-AQM), whose small size demanded attention. Early versions of the microAnalyzer™ were thoroughly tested and the results showed great promise for it to meet or exceed the performance of the VOA. Two AQMs were prepared as a station detailed test objective (SDTO) and flown to ISS aboard the Space Shuttle in March 2009. The purpose of the SDTO was to evaluate the AQM performance, in the intended operational environment, as a replacement for the VOA. This paper will present a brief overview of the AQM technology (gas chromatography/differential mobility spectrometry) and briefly discuss the flight preparation of the AQM for the SDTO. The major portion of the paper will be devoted to on-orbit results and comparison of data from simultaneously acquired AQM runs and archival samples.

A Second Generation Volatile Organic Analyzer for the International Space Station

Early in the development of the Crew Health Care System (CHECS) for the International Space Station (ISS), it was recognized that detection of target volatile organic compounds would be a key component of the air monitoring strategy. Experiences during the NASA/Mir program supported the decision to include a real-time volatile organic analyzer (VOA) aboard ISS to help assess the impact of air quality events on crew health and determine the effectiveness of decontamination efforts. Toward this end, a joint development by the Toxicology Laboratory at Johnson Space Center and Graseby Dynamics produced a VOA that has been delivered and is ready for the first 5 years of ISS operation. The first-generation VOA selection criteria included minimizing size, weight, and power consumption while maintaining analytical performance. Measuring available technologies against these criteria, a VOA system based upon gas chromatography/ion mobility spectrometry (GC/IMS) was selected in the mid-90s. However, as NASA looks forward to later-stage ISS operations and to new frontiers such as human exploration of Mars, the ISS VOA (weighing 43 kg and consuming 160 watts) must be replaced by a smaller, less resource-intensive device. This paper will present a possible second-gene ration VOA based upon the same technology as the first-generation unit. Utilizing GC/IMS technology again will permit the instrumental data and experience gained during the initial phase of ISS to be applied to later ISS phases and advanced spacecraft missions. During the past 3 years, efforts to reduce the size of ion mobility spectrometers have been pursued by Graseby Dynamics, the manufacturer of the first-generation VOA. The concept of operation, expected analytical performance, and estimated size of a fully functional second-generation VOA based upon GC/mini-IMS technology will be presented. Furthermore, results of initial laboratory evaluations will be shown.