Analysis of Volatile Organic Compounds on Mir Station

Objectives

The increasing long-term presence of humans in space requires the development of increasingly complex life support systems. Therefore, some means of air quality monitoring is needed to provide detailed information on air composition and ensure crew health.

The objective of the "Analysis of Volatile Organic Compounds on Mir Station" investigation was to characterize volatile organic compounds (VOCs) in air samples taken from the Mir Space Station using new technology based on direct sampling ion trap mass spectrometry (DSITMS). The results of this research will provide detailed information on the types and concentration of VOCs in the Mir environment. Moreover, the demonstration of new technology and comparison against proven methods will yield valuable information on the feasibility of its use for monitoring air quality in advanced life support systems.

Shuttle-Mir Missions
Mir 19, Mir-21/NASA-2, Mir-22/NASA-3, Mir-23/NASA-4, Mir-24/NASA-5, Mir-25/NASA-6

Approach
Twenty-four hour time-averaged air samples were collected using the solid sorbent air sampler (SSAS), and grab samples were collected using grab sample containers (GSC). Samples were then transferred from Mir via the Space Shuttle to the Toxicology Laboratory at Johnson Space Center (JSC) for analysis and sample subdivision, and then sent on to San Francisco State University (SFSU) for ion trap mass spectrometry and gas chromatography analysis. Standard operating procedures, quality control samples and confirmatory experiments were employed to ensure reliable, high-quality data. Analyses were performed via a modified form of EPA-approved gas chromatography/mass spectrometry (GC/MS) methods and new techniques based on direct sampling ion trap mass spectrometry (DSITMS). Significant effort was put into developing, testing and demonstrating DSITMS techniques with the real-time monitoring of trace-level contaminants in air.

Results
Volatile organic compound (VOC) types and concentrations on Mir were successfully identified using both GC/MS and DSITMS methods, and the Mir air quality was found to meet NASA specifications. Comparing the two methods, GC/MS was clearly capable of detecting a wide range of VOCs at far lower concentrations than DSITMS. However, DSITMS methods are still under development and offer a number of potential advantages over GC/MS. Although detection limits are currently higher than GC/MS, this is a function of the relative amounts of samples entering the detector, which are on the order of 10-100 ml for GC/MS and 10-100 ml for DSITMS. Recent work using alternate sample introduction systems for DSITMS show promise in reducing detection limits significantly. Moreover, given that all but a few of the target VOCs have spacecraft maximum allowable concentrations (SMACs) in the parts per million (ppm) range, it is apprarent that DSITMS techniques employed here are more than adequate for monitoring most VOCs at concentrations well below their SMACs. Finally, the instrumentation for DSITMS is far simpler and would ultimately require much less space, weight and power on a space platform.

Earth Benefits
The air sampling devices developed and employed by NASA, in particular, the Solid Sorbent Air Sampler (SSAS), have practical applications for sampling air pollution in closed spaces from which ill health effects may result. For example, these devices can be used to sample air in submarines and commercial aircraft.

Publications
Palmer, P.T., C.M. Wong, R.A. Yost, N.A. Yates, and T.M. Griffin, "Advanced Automation for Ion Trap Mass Spectrometry - New Opportunities for Real-Time, Autonomous Analysis", in Artificial Intelligence Applications in Chemistry, S. Brown (Ed.), Wiley, 1996, pp. 25-60.

Palmer, P.T., X. Fan, C. Remigi, B. Nies, and L. Lee, "Direct Sampling Ion Trap Mass Spectrometry - A Growing Toolkit for Air Monitoring Applications", SAE technical paper series 981743.

Palmer, P.T., D. Karr and Carla Remigi, "Evaluation of Two Different Direct Sampling Ion Trap Mass Spectrometry Methods for Monitoring Volatile Organic Compounds in Air", Journal of the Field Analytical Chemistry and Technology, manuscript submitted.

Principal Investigators
Peter T. Palmer, Ph.D.
San Francisco State University

Valentina Savina, M.D.
Institute of Biomedical Problems

Co-Investigators
Warren Belisle

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