Predicting Air Quality at First Ingress into Vehicles Visiting the International Space Station.

INTRODUCTION: NASA regularly performs ground-based offgas tests (OGTs), which allow prediction of accumulated volatile pollutant concentrations at first entry on orbit, on whole modules and vehicles scheduled to connect to the International Space Station (ISS). These data guide crew safety operations and allow for estimation of ISS air revitalization systems impact from additional pollutant load. Since volatiles released from vehicle, module, and payload materials can affect crew health and performance, prediction of first ingress air quality is important. METHODS: To assess whether toxicological risk is typically over or underpredicted, OGT and first ingress samples from 10 vehicles and modules were compared. Samples were analyzed by gas chromatography and gas chromatography-mass spectrometry. The rate of pollutant accumulation was extrapolated over time. Ratios of analytical values and Spacecraft Maximum Allowable Concentrations were used to predict total toxicity values (T-values) at first entry. Results were also compared by compound. RESULTS: Frequently overpredicted was 2-butanone (9/10), whereas propanal (6/10) and ethanol (8/10) were typically underpredicted, but T-values were not substantially affected. Ingress sample collection delay (estimated by octafluoropropane introduced from ISS atmosphere) and T-value prediction accuracy correlated well (R2 = 0.9008), highlighting the importance of immediate air sample collection and accounting for ISS air dilution. DISCUSSION: Importantly, T-value predictions were conservative 70% of the time. Results also suggest that T-values can be normalized to octafluoropropane levels to adjust for ISS air dilution at first ingress. Finally, OGT and ingress sampling has allowed small leaks in vehicle fluid systems to be recognized and addressed.Romoser AA, Scully RR, Limero TF, De Vera V, Cheng PF, Hand JJ, James JT, Ryder VE. Predicting air quality at first ingress into vehicles visiting the International Space Station. Aerosp Med Hum Perform. 2017; 88(2):104-113.

Microplasma Ionization of Volatile Organics for Improving Air/Water Monitoring Systems On-Board the International Space Station.

Low molecular weight polar organics are commonly observed in spacecraft environments. Increasing concentrations of one or more of these contaminants can negatively impact Environmental Control and Life Support (ECLS) systems and/or the health of crew members, posing potential risks to the success of manned space missions. Ambient plasma ionization mass spectrometry (MS) is finding effective use as part of the analytical methodologies being tested for next-generation space module environmental analysis. However, ambient ionization methods employing atmospheric plasmas typically require relatively high operation voltages and power, thus limiting their applicability in combination with fieldable mass spectrometers. In this work, we investigate the use of a low power microplasma device in the microhollow cathode discharge (MHCD) configuration for the analysis of polar organics encountered in space missions. A metal-insulator-metal (MIM) structure with molybdenum foil disc electrodes and a mica insulator was used to form a 300 µm diameter plasma discharge cavity. We demonstrate the application of these MIM microplasmas as part of a versatile miniature ion source for the analysis of typical volatile contaminants found in the International Space Station (ISS) environment, highlighting their advantages as low cost and simple analytical devices. Graphical Abstract ᅟ.

Electrothermal Vaporization Sample Introduction for Spaceflight Water Quality Monitoring via Gas Chromatography-Differential Mobility Spectrometry.

In the history of manned spaceflight, environmental monitoring has relied heavily on archival sampling. However, with the construction of the International Space Station (ISS) and the subsequent extension in mission duration up to one year, an enhanced, real-time method for environmental monitoring is necessary. The station air is currently monitored for trace volatile organic compounds (VOCs) using gas chromatography-differential mobility spectrometry (GC-DMS) via the Air Quality Monitor (AQM), while water is analyzed to measure total organic carbon and biocide concentrations using the Total Organic Carbon Analyzer (TOCA) and the Colorimetric Water Quality Monitoring Kit (CWQMK), respectively. As mission scenarios extend beyond low Earth orbit, a convergence in analytical instrumentation to analyze both air and water samples is highly desirable. Since the AQM currently provides quantitative, compound-specific information for air samples and many of the targets in air are also common to water, this platform is a logical starting point for developing a multimatrix monitor. Here, we report on the interfacing of an electrothermal vaporization (ETV) sample introduction unit with a ground-based AQM for monitoring target analytes in water. The results show that each of the compounds tested from water have similar GC-DMS parameters as the compounds tested in air. Moreover, the ETV enabled AQM detection of dimethlsilanediol (DMSD), a compound whose analysis had proven challenging using other sample introduction methods. Analysis of authentic ISS water samples using the ETV-AQM showed that DMSD could be successfully quantified, while the concentrations obtained for the other compounds also agreed well with laboratory results.

Electro-thermal vaporization direct analysis in real time-mass spectrometry for water contaminant analysis during space missions.

The development of a direct analysis in real time-mass spectrometry (DART-MS) method and first prototype vaporizer for the detection of low molecular weight (∼30-100 Da) contaminants representative of those detected in water samples from the International Space Station is reported. A temperature-programmable, electro-thermal vaporizer (ETV) was designed, constructed, and evaluated as a sampling interface for DART-MS. The ETV facilitates analysis of water samples with minimum user intervention while maximizing analytical sensitivity and sample throughput. The integrated DART-ETV-MS methodology was evaluated in both positive and negative ion modes to (1) determine experimental conditions suitable for coupling DART with ETV as a sample inlet and ionization platform for time-of-flight MS, (2) to identify analyte response ions, (3) to determine the detection limit and dynamic range for target analyte measurement, and (4) to determine the reproducibility of measurements made with the method when using manual sample introduction into the vaporizer. Nitrogen was used as the DART working gas, and the target analytes chosen for the study were ethyl acetate, acetone, acetaldehyde, ethanol, ethylene glycol, dimethylsilanediol, formaldehyde, isopropanol, methanol, methylethyl ketone, methylsulfone, propylene glycol, and trimethylsilanol.