Advances in offline approaches for chemically speciated measurements of trace gas-phase organic compounds via adsorbent tubes in an integrated sampling-to-analysis system

Gas-phase organic compounds across a range of volatilities, including volatile organic compounds (VOCs), are key components of outdoor air, indoor spaces, and a variety of other anthropogenic and biogenic systems. The collection of offline samples on adsorbent-packed tubes for analysis on laboratory instrumentation has been in use for decades, but with limited sensitivities and compound coverage. We present and evaluate our integrated sampling-to-analysis system that enables offline detailed chemical characterization of multi-faceted organic mixtures at trace concentrations. Its capabilities extend across a diverse variety of VOCs with different molecular features, as well as intermediate and semivolatile organic compounds (I/SVOCs). Samples can be collected manually or via automated devices that have been applied in chamber, field, and aircraft platforms. The laboratory instrumentation can be coupled to both a high resolution mass spectrometer (MS) and a traditional quadrupole MS, though performance metrics presented in this study are determined via the traditional MS. We demonstrate capabilities for detailed chemical characterization and routine performance for a wide range of compound functionalities at sub-part per trillion (ppt) concentrations, and as low as <100 parts per quadrillion (ppq), yielding 3300 observed unique compound peaks in a single indoor air sample. These limits of detection and compound coverage were accomplished through a holistic optimization of the entire system and lifecycle of adsorbent tubes. We present our best practices for all aspects of tube production, handling, sampling, and analysis, and an examination of commercially-available materials and our custom adsorbent tubes using a diverse mix of VOC, IVOC, and SVOC standards, including difficult to measure analytes across a range of polarities and functionalities. In many aspects, the commercially-available materials and tube conditioners tested were insufficient for achieving low-ppt measurements

Advances in offline approaches for chemically speciated measurements of trace gas-phase organic compounds via adsorbent tubes in an integrated sampling-to-analysis system

Gas-phase organic compounds across a range of volatilities, including volatile organic compounds (VOCs), are key components of outdoor air, indoor spaces, and a variety of other anthropogenic and biogenic systems. The collection of offline samples on adsorbent-packed tubes for analysis on laboratory instrumentation has been in use for decades, but with limited sensitivities and compound coverage. We present and evaluate our integrated sampling-to-analysis system that enables offline detailed chemical characterization of multi-faceted organic mixtures at trace concentrations. Its capabilities extend across a diverse variety of VOCs with different molecular features, as well as intermediate and semivolatile organic compounds (I/SVOCs). Samples can be collected manually or via automated devices that have been applied in chamber, field, and aircraft platforms. The laboratory instrumentation can be coupled to both a high resolution mass spectrometer (MS) and a traditional quadrupole MS, though performance metrics presented in this study are determined via the traditional MS. We demonstrate capabilities for detailed chemical characterization and routine performance for a wide range of compound functionalities at sub-part per trillion (ppt) concentrations, and as low as <100 parts per quadrillion (ppq), yielding 3300 observed unique compound peaks in a single indoor air sample. These limits of detection and compound coverage were accomplished through a holistic optimization of the entire system and lifecycle of adsorbent tubes. We present our best practices for all aspects of tube production, handling, sampling, and analysis, and an examination of commercially-available materials and our custom adsorbent tubes using a diverse mix of VOC, IVOC, and SVOC standards, including difficult to measure analytes across a range of polarities and functionalities. In many aspects, the commercially-available materials and tube conditioners tested were insufficient for achieving low-ppt measurements

The Impact of Particle Size, Relative Humidity, and Sulfur Dioxide on Iron Solubility in Simulated Atmospheric Marine Aerosols

Iron is a limiting nutrient in about half of the world’s oceans, and its most significant source is atmospheric deposition. To understand the pathways of iron solubilization during atmospheric transport, we exposed size segregated simulated marine aerosols to 5 ppm sulfur dioxide at arid (23 ± 1% relative humidity, RH) and marine (98 ± 1% RH) conditions. Relative iron solubility increased as the particle size decreased for goethite and hematite, while for magnetite, the relative solubility was similar for all of the fine size fractions (2.5–0.25 μm) investigated but higher than the coarse size fraction (10–2.5 μm). Goethite and hematite showed increased solubility at arid RH, but no difference (<i>p</i> > 0.05) was observed between the two humidity levels for magnetite. There was no correlation between iron solubility and exposure to SO₂ in any mineral for any size fraction. X-ray absorption near edge structure (XANES) measurements showed no change in iron speciation [Fe­(II) and Fe­(III)] in any minerals following SO₂ exposure. SEM-EDS measurements of SO₂-exposed goethite revealed small amounts of sulfur uptake on the samples; however, the incorporated sulfur did not affect iron solubility. Our results show that although sulfur is incorporated into particles via gas-phase processes, changes in iron solubility also depend on other species in the aerosol

Genetic and immunologic evaluation of children with inborn errors of immunity and severe or critical COVID-19

Background: Most severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected individuals are asymptomatic or only exhibit mild disease. In about 10% of cases, the infection leads to hypoxemic pneumonia, although it is much more rare in children. Objective: We evaluated 31 young patients aged 0.5 to 19 years who had preexisting inborn errors of immunity (IEI) but lacked a molecular diagnosis and were later diagnosed with coronavirus disease 2019 (COVID-19) complications. Methods: Genetic evaluation by whole-exome sequencing was performed in all patients. SARS-CoV-2-specific antibodies, autoantibodies against type I IFN (IFN-I), and inflammatory factors in plasma were measured. We also reviewed COVID-19 disease severity/outcome in reported IEI patients. Results: A potential genetic cause of the IEI was identified in 28 patients (90.3%), including mutations that may affect IFN signaling, T- and B-cell function, the inflammasome, and the complement system. From tested patients 65.5% had detectable virus-specific antibodies, and 6.8% had autoantibodies neutralizing IFN-I. Five patients (16.1%) fulfilled the diagnostic criteria of multisystem inflammatory syndrome in children. Eleven patients (35.4%) died of COVID-19 complications. All together, at least 381 IEI children with COVID-19 have been reported in the literature to date. Although many patients with asymptomatic or mild disease may not have been reported, severe presentation of COVID-19 was observed in 23.6% of the published cases, and the mortality rate was 8.7%. Conclusions: Young patients with preexisting IEI may have higher mortality than children without IEI when infected with SARS-CoV-2. Elucidating the genetic basis of IEI patients with severe/critical COVID-19 may help to develop better strategies for prevention and treatment of severe COVID-19 disease and complications in pediatric patients