ANYL Sem Abstracts

This page contains the abstracts for upcoming and past Analytical & Environmental Chemistry Seminars at CU. Please post newer seminars at the top, but do not erase the abstracts from old seminars.

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Monday, January 31, 2011

Title and Abstract Forthcoming

Prof. Mark Hernandez

Monday, November 29, 2010

Ground based FTIR and MAXDOAS column observations of atmospheric trace gases

Ivan Ortega

Abstract

Carbon monoxide (CO) and Nitrogen dioxide (NO2) are important pollutants in urban agglomerations. Even though surface concentrations of those pollutants have been monitored routinely, the quantification of the total load (vertical column integral of concentration over the boundary layer height) is challenging because surface concentrations may not be representative over height of the boundary layer; the vertical distribution may further be variable. This presentation consists of two parts describing the measurement and retrieval techniques as well as results for CO and NO2 in two very different urban environments, Mexico City and Los Angeles, CA.

The diurnal trend of columnar CO in the boundary layer of Mexico City has been measured during one year with ground-based infrared absorption spectroscopy. Daytime CO total columns are retrieved from measured solar spectra and for the first time, nocturnal CO total columns using moonlight have been retrieved within a megacity. The measurements were taken at the Universidad Nacional Autonoma de Mexico (UNAM) campus located in Mexico City (19.33N, 99.18W, 2260 m.a.s.l.) from October 2007 to October2008 with a Fourier-transform infrared spectrometer (FTIR) at 0.5 cm-1 resolution.

An overview of measurements with a MAXDOAS instrument deployed at the Caltech supersite in Pasadena, CA this year will be presented in the second part of this talk. Validation of real time slant column densities of NO2 will be presented from the period of May to June 2010 in Pasadena, CA as part of CALNEX campaign. Using a geometric approximation NO2 vertical column densities are retrieved. The degree of mixing in the boundary layer is assessed by comparison of the NO2 vertical column densities with NO2 mixing ratios as measured from a cavity enhanced DOAS instrument located on top of Millikan Library, and independent measurements of mixing height by ceilometers.

Monday, November 15, 2010

Isotopic Labeling of Early Earth Haze Analogs

Raea Lessard

Abstract

The Faint Young Sun paradox predicts that the surface temperature of the early Earth was below the freezing point of water. A cold Earth is the expected outcome of an atmosphere composed of nitrogen and trace amounts of carbon dioxide coupled with a sun whose intensity was only 70% of its current luminosity. However, a cold Earth contrasts with the geologic record, which suggests that the early Earth was warm and had liquid water on its surface. The paradox can be resolved by adding methane, a strong greenhouse gas, to the weakly warming atmosphere assumed in the paradox. We have shown that atmospheres composed of nitrogen and trace amounts of methane and carbon dioxide will produce a haze when irradiated by light at the Lyman-a wavelength (121.6 nm). Such a haze would have implications for the early climate, as well as for the origin and evolution of life.

Now that the possibility of haze has been demonstrated, some questions remain: What is its composition? How is it made? To answer these questions, we label each of the carbon sources with 13C and use an aerosol mass spectrometer (AMS) to observe the haze fragments generated by electron impact ionization. We aim to use the information generated by the AMS, coupled with isotopic labeling, to elucidate the chemical pathway(s) by which the haze is made. In this talk, we share preliminary results from these experiments, demonstrate the feasibility of the proposed methods in elucidating the pathway(s), and touch on future work.

Monday, November 1, 2010

Levoglucosan, S-Phenylmercapturic Acid, and S-Benzylmercapturic Acid as Urinary Biomarkers of Wood Smoke Exposure

Callie Cole

Abstract

Wood smoke (WS) inhalation is a source of adverse health effects in humans due to its toxic and carcinogenic constituents. Monitoring exposure levels to WS through the use of urinary biomarkers can support epidemiological studies involving the direct health effects of exposure and help evaluate the effectiveness of efforts to limit human exposure in the future. Studies on levoglucosan showed that the diet has too large of an influence on its urinary concentration to conclusively quantify WS exposure. This project focuses on two other potential urinary biomarkers, s-phenylmercapturic acid (SPMA) and s-benzylmercapturic acid (SBMA), that have been previously successful for monitoring environmental tobacco smoke and industrial smoke exposure in humans, and studies their effectiveness in quantifying WS exposure. The hypothesis of this study is that both SPMA and SBMA will be effective biomarkers of WS exposure. To test this hypothesis, methods for the extraction and analysis of these compounds from urine were developed, evaluated and applied to the urine of exposed and control human subjects. The analytical method was found to have a limit of detection of 10ppb and a limit of quantitation of 50 ppb. Analyses of urine from individuals before and after exposure to WS showed quantifiable levels of the markers in 60% of samples, did not reveal a significant increase or decrease in concentrations of biomarkers in post-exposure relative to pre-exposure samples. The results imply that these biomarkers may not be suitable to determine exposure to WS. Additional studies to improve the extraction and detection sensitivity and reproducibility, as well as to monitor urinary levels over longer periods of time pre- and post exposure are needed to conclusively determine the utility of these markers.

A Molecularly Imprinted Polymer as a Sensor for Nicotine

Brett Palm

Abstract

Molecularly imprinted polymers (MIP) have been shown to preferentially bind molecules with specific shape or functional groups. This technology is discussed as it relates to the development of a nicotine sensor. Qualitative results are shown using an Atomic Force Microscope and FTIR spectra, and progress is made towards quantitative analysis using a GC.

Monday, October 25, 2010

Copper Binding by Dissolved Organic Matter using Competitive Ligand Exchange- Solid Phase Extraction and Application to the Biotic Ligand Model

Alison Craven

Abstract

The toxicity of copper to aquatic organisms is dependent on the aqueous copper speciation. The free copper concentration (Cu2+) primarily controls the toxicity of copper to fish due to its adsorption in the gill (a “biotic ligand”). Copper binding by dissolved organic matter plays a significant role in copper speciation and toxicity by reducing the amount of free copper that can bind to the biotic ligand. The biotic ligand model (BLM) is a model that predicts the concentration of free copper as a function of pH, dissolved organic matter concentration, and water hardness. While the model includes dissolved organic matter, there is still much uncertainty as to the correct copper-dissolved organic matter binding constants to include in the model. Much work has been done to measure the conditional stability constants for the copper-dissolved organic matter complex, but the methods used to measure these stability constants have “detection window” limitations that are not always recognized by those incorporating the stability constants into toxicity models. In this study, the competitive ligand exchange-solid phase extraction (CLE-SPE) method was used to measure the stability constants at pH 6.5 and 0.01 ionic strength over a wide range of Cu:dissolved organic matter concentration ratios. A comparison of the CLE-SPE stability constants with those measured by other methods revealed that the most important factor to determine the binding strength is the ratio of Cu:dissolved organic matter concentration, even for dramatically different environmental and experimental conditions. The Cu:dissolved organic matter concentration ratio is important because as the ratio decreases, the binding constant increases due to the heterogeneity of binding sites present in dissolved organic matter. Results obtained from this study can be used in the BLM to more accurately predict the role of dissolved organic matter in copper speciation.

Monday, October 4, 2010

Eddy-covariance measurements with time-of-flight mass spectrometry: A new approach to chemically-resolved organic particle and gas fluxes

Delphine K. Farmer

Abstract

Although laboratory studies show that biogenic VOCs yield significant secondary organic aerosol, emission of biogenic SOA fluxes has not yet been conclusively observed over forests. Further, while aerosols are known to deposit to forest surfaces, the chemical identity and ecosystem implications of this deposition flux remains undetermined. To better constrain sources and sinks of biogenic SOA, we have developed a new technique to directly measure fluxes of chemically resolved aerosol over forests using the High Resolution Time-of-Flight Aerosol Mass Spectrometer in a new, fast eddy covariance mode. This approach allows us to quantitatively identify both organic and inorganic components, including NH4+ , SO4_2- and NO3- , and has been deployed over both temperate and tropical forests. Results show both upward and downward fluxes of aerosol, including deposition of NH4+ . Differences in direction and magnitude of different chemical components provide insight on aerosol chemistry and potential ecosystem effects. In particular, we observe evidence for rapid formation or growth of biogenic SOA within both temperate and tropical forest canopies.

Aerosol Composition in Los Angeles During the 2010 CalNex Campaign Studied by High Resolution Aerosol Mass Spectrometry

Patrick L. Hayes

Abstract

Submicron atmospheric aerosols impact climate and human health, but their sources and composition are poorly understood. To address this knowledge gap, high-resolution time-of-flight aerosol mass spectrometry (AMS) and other advanced instrumentation were deployed during the CalNex field campaign in May and June 2010 to characterize the composition of aerosols in the Los Angeles area. Utilizing AMS, the concentrations for both organic and non-refractory inorganic (sulfate, nitrate, ammonium, chloride) submicron aerosols were quantified at the Pasadena ground site 15 km NE of downtown Los Angeles. Nitrate aerosols appear to dominate in the cooler mornings, but their concentration is reduced in the afternoon when organic aerosols (OA) increase and dominate. The diurnal variations in concentration are strongly influenced by vertical dilution from the rising planetary boundary layer in the afternoon. The concentrations of oxygenated OA (OOA), and hydrocarbon-like OA (HOA) are estimated, and it is found that OOA is consistently the largest type of OA present (~75% of the total OA concentration). This result indicates that the air mass over the site has undergone substantial chemical aging. The correlations between OOA and Ox (O3 + NO2) concentrations, as well as between HOA, CO and black carbon concentrations are consistent with previous studies. Ultimately, the goal of this research will be to test the accuracy of recently-proposed SOA models by combining the characterization of SOA with measurements of precursor and oxidant concentrations carried out concurrently during CalNex.

Monday, September 27, 2010

Update on RASEI, Solar Fuels, and Critical Areas of Electrochemical Energy Research

Carl A. Koval

Abstract

Since 2006, my primary responsibility has been the creation and development of CU-Boulder’s Energy initiative, which became the Renewable and Sustainable Energy Institute (RASEI). The first part of my presentation will be to reflect how RASEI got to where it is and, hopefully, where it is going. The second part will focus on how large-scale solar production of hydrogen is likely to be the first step towards creating a solar fuels industry. Finally, I will briefly describe three critical areas of energy research that the (photo)electrochemistry community needs to address.

Organic Aerosol Sources and Processing in the Atmosphere

Jose L. Jimenez

Abstract

Organic aerosols (OA) account for about 1/2 of the submicron particle mass in the atmosphere, but their sources, sinks, and evolution are poorly understood. OA is comprised of primary OA (emitted in the particle phase) and secondary OA (formed from chemical reactions of gas-phase species). In this talk I will summarize research in OA by our group over the last year, including a summary of the recent CalNex-LA field project in Pasadena (CA), research on the SOA formation and photochemical evolution of biomass burning emissions, on SOA model/measurement comparisons in different environments, and on collaborative work with global modelers to constraint the global OA budget. I will also discuss upcoming projects including characterization and use of semicontinuous GC-MS and chemical ionization mass spec. to analyze OA, and field projects in the Rocky Mountains, India, and Southeast Asia.

Monday, September 20, 2010

Nanoscale Therapeutics in the Treatment of Multidrug Resistant Pathogens

Daniel Feldheim

Abstract

In the past century, great strides have been made in the design and synthesis of pharmaceutical compounds for the treatment of human disease. Diseases such as breast cancer and chronic mylogenous leukemia, once thought to be completely untreatable, are now survived by a large percentage of patients. However, there is a large number of pressing medical issues related to the use of small-molecule drugs that must be addressed. For example, the emergence of drug-resistant bacterial and viral strains represent significant global medical challenges to overcome in the 21st century. To provide the tools to potentially treat infectious diseases, we have been developing ligand-coated gold nanoparticles as a new paradigm for drug discovery. Our work to date has offered some hope that the gold nanoparticle therapeutic platform may be a promising one in the search for new treatments for viral and bacterial disease. A few examples from our labs are the use of 2.0 nm diameter ligand-coated gold nanoparticles in the prevention of HIV fusion to human cells, and in the growth inhibition of E. coli and methicillin-resistant S. aureus. These results have inspired us to think in new ways about gold nanoparticle-based therapeutic design and the molecular-level design parameters that may influence activity. This talk will discuss some of these considerations.

The First Inhalable Dry Powder Measles Vaccine Entering Clinical Trials

Robert E. Sievers

Abstract

Ten percent of all pre-school deaths in India are measles-related. We have developed a Measles Vaccine, Dry Powder (MVDP) and PuffHaler® a novel dry powder inhaler for respiratory delivery to overcome the safety and vaccine wastage problems associated with the current injectable vaccine. MVDP was manufactured from bulk liquid, live attenuated, measles vaccine using CAN-BD® to yield a stable, dry powder, with fine particles suitable for aerosolization and delivery to the pulmonary tract by inhalation. This was achieved by substituting myo-inositol for sorbitol as a stabilizing sugar that is less hygroscopic. Contact with water is detrimental to the stability of measles vaccine and the microparticles are reconstituted only when they deposit in the moist surfaces of the respiratory tract. There is no need for purified water to be carried to remote locations. The particles dried by CAN-BD are homogeneous; the vaccine viral activity distribution in the 1 to 5 micron aerodynamic diameter microparticles is the same as the mass distribution, within experimental error. The shelf life is excellent at 2 to 8 °C with only about 0.5 log loss of activity after more than 2 years. At 25 °C, there is approximately 0.8 log loss after 6 months of storage. The immunogenicity and protective efficacy of a primary dose of MVDP delivered was tested in non-anesthetized, free breathing, Rhesus macaques. MVDP induced MV-specific humoral and T-cell responses at least as robust as subcutaneous measles vaccine and completely protected macaques from infection with wild type measles virus without adverse effects. Phase I clinical trials are now scheduled.

Monday, September 13, 2010

Sulfur Particles on Early Earth

Margaret A Tolbert

Understanding the atmosphere of the early Earth during the Archean, the period of time approximately 4 – 2.45 billion years ago, is an important part of understanding the conditions under which life originated and developed. While the atmospheric composition in highly uncertain during this time, it is likely that volcanic activity released sulfur dioxide into the air. Because of the lack of oxygen on the early Earth, the atmospheric chemistry of sulfur is expected to be quite different than on present day Earth. It has been suggested that atmospheric reactions in a reducing atmosphere could favor S8 particles over sulfuric acid particles. Here we use aerosol mass spectrometry to probe the chemical composition of particles formed from reactions of sulfur dioxide under a range of atmospheric conditions. Implications for the early Earth are discussed.

A heterogeneous open ocean source for glyoxal and iodine oxide

Rainer Volkamer

The climate relevance of biologically active ocean upwelling regions has primarily been studied in terms of the air-sea partitioning of long-lived greenhouse gases (e.g., CO2, CH4, N2O etc), and the release of the reactive gas DMS, which can form aerosols as a result of atmospheric transformations. Considerably less attention has been paid to open ocean sources of other reactive gases that, like DMS, can form aerosols. Such molecules are glyoxal (CHOCHO) and iodine oxide (IO). Glyoxal is an indicator for oxidative hydrocarbon chemistry, and a building block for secondary organic aerosol (SOA). SOA modifies the hygroscopic properties of organic aerosols, and potentially also adds to the growth of small particles to sizes that can more easily activate to form cloud droplets. Iodine oxide (IO) can nucleate new particles, and/or add to the growth of pre-existing particles. Due to the very high solubility of the glyoxal molecule, concentrations in excess of 100ppt over the open ocean like we found over the Pacific Ocean require an airborne source mechanism (Sinreich et al., 2010). We have investigated the source mechanism further during a ship campaign in 2009, as well as a first research flight aboard the NSF/NCAR GV research aircraft (HIAPER). Both campaigns give clues about the sources of both gases over the remote tropical Pacific Ocean, and reveal a surprising impact on the composition of the free troposphere.

Tuesday, April 27, 2010

Laboratory Studies of Titan Tholins

Raea Lessard

Saturn’s moon Titan is enshrouded in a thick orange haze. A similar haze may have formed on the early Earth and provided the organic compounds necessary for the emergence of life. This talk will present results from several laboratory studies focusing on the manipulation of Titan aerosols, also known as tholins, for chemical analysis and simulation of prebiotic processing. Analysis techniques include nuclear magnetic resonance (NMR) and sizing by the scanning mobility particle sizer (SMPS). This will be followed by preliminary results from in-situ analysis by the Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) of tholins formed at a range of pressures.

Tuesday, April 13, 2010

DOAS Measurements of Halogen Oxides

Hilke Oetjen

Halogens species are of outmost importance to the atmosphere due to their potential to destroy ozone and the DOAS (differential optical absorption spectroscopy) method is a powerful tool to measure halogen oxides like IO, BrO, but also OClO. After a brief introduction to the longpath-DOAS and multi-axes-DOAS techniques, this talk will present results from several field studies focusing mainly on the observations of iodine and bromine oxides and their impact on the marine boundary layer. This will be followed by a brief excursion to the stratosphere and the chlorine chemistry of the polar ozone hole. The third part of the talk will give an outlook on the future deployment of an airborne multi-axis (AMAX) DOAS instrument in the CalNex campaign in California this summer.

Tuesday, April 6, 2010

Single Particle Studies of Aerosol Hygroscopicity, Aging and Mass Accommodation

Professor Jonathan P. Reid, School of Chemistry, University of Bristol, UK

Abstract

Studies of the processes that govern the physical and chemical transformation of aerosol particles are crucial for improving our understanding of the properties of atmospheric aerosol. In particular, the equilibrium state is governed by hygroscopicity, the vapour pressures of semi-volatile organic components, and mixing state. Aerosol optical tweezers can provide a method for isolating single particles, or multiple particles of distinct composition for comparison. When combined with cavity enhanced Raman spectroscopy, particle size, composition and morphology can be characterised in detail. We will first examine how such an approach can allow an examination of the equilibrium state of aerosol. Measurements of the chemical aging of mixed component aerosol (oleic acid/sodium chloride/water) by ozone will then be reported. Finally, a novel approach for probing the kinetics of the mass transfer accompanying condensation or evaporation of water will be described and first measurements reported.

Tuesday, March 30, 2010

Development and Application of a Metastable Atom Bombardment (MAB) Source for Penning Ionization Time-of-Flight Aerosol Mass Spectrometry

Carly Robinson

Abstract

The Aerodyne time-of-flight aerosol mass spectrometer (ToF-AMS) utilizes thermal vaporization followed by electron ionization (EI) to convert aerosol components to gas-phase ions. The method enables quantification of chemical classes, but the extensive fragmentation caused by EI limits the specificity of both chemical analysis and source identification by factor analysis. To better identify the molecular components of aerosols, we have constructed a metastable atom bombardment (MAB) ionization source that can be interfaced to standard ToF-AMS hardware. A beam of metastable rare gas atoms is produced by a low-voltage DC discharge and focused toward the vaporization plume, yielding Penning Ionization of the analyte molecules. By changing gases, the excited energies of the metastables can be adjusted between 20.61 eV (He) and 9.92 eV (Kr). Source parameters, including pressures, current, geometry, and materials, were optimized for He, Ar, and Kr. Instrument sensitivity and induced fragmentation was characterized for each using lab-generated oleic acid particles. The demonstrated sensitivities are 0.1% of EI (3% of the SNR of EI in the V-mode, comparable to the Q-AMS SNR), which is sufficient for ambient monitoring. A metastable flux of 2.6e14 sr-1sec-1 has been achieved. The MAB-AMS has been deployed to the FLAME-3 campaign at the USDA Fire Sciences Laboratory in Missoula, MT, and used to sample smoke from open burning of different biomass samples.

Tuesday, March 16, 2010

Hugh Coe, Prof. of Atmospheric Composition, University of Manchester, UK

Title: "Secondary Aerosol Composition and Properties: A contrast between European Pollution and Tropical Biogenic Environments"

Abstract: This talk will describe a number of recent studies of secondary aerosol properties and processes in two contrasting environments - European pollution, sampled during the EUCAARI Intensive study in May 2008, and a clean tropical biogenic environment, sampled during the Oxidants and Particle Production Potential (OP3) study in Borneo, also in 2008. The EUCAARI project aims to advance our understanding of climate and air quality by integrating laboratory studies, both short and long term field investigations, satellite data, and modeling at regional and global scales. I will present airborne observations taken during an intensive study to provide a local and regional scale overview of the general composition trends of atmospheric aerosol over northern Europe.

The time dependent measurements obtained by aerosol mass spectrometry enable the chemical transformation time scales of aerosol material to be explored. In particular, factor analyses of the observed organic mass spectral fingerprint demonstrates the continuum nature of chemical processing. Ammonium nitrate is an important aerosol component in NW Europe. It exists in a temperature dependent equilibrium which favours particulate formation in the moist, cool upper portion of the boundary layer. We have shown that this results in aerosol optical depths inferred from ground based measurements are biased low by up to 50% by comparison with AERONET, aircraft measurements, and lidar data during periods of high AOD in anticyclonic conditions. The ubiquitous nature of black carbon (BC) was also demonstrated and how this is processed by secondary particulate will be shown using single particle soot photometry. These topics will all be explored and comparison with global model studies will also be discussed. In contrast, tropical environemnts are dominated by transport of aerosol into the region, by primary production of biological material in the coarse mode aerosol or by secondary organic aerosol produced within the region by photochemical oxidation of precursors. These will presented and the properties of secondary organic material compared with other tropical sites and with global models.

TUESDAY, March 9, 2010

Nathalie Carrasco, Laboratoire Atmosphères, Milieux, Observations Spatiales, IPSL, Verrières le Buisson, France

Title: Experimental simulation of Titan’s atmosphere by a radio-frequency plasma

• Recent papers: JPCA-2009, JPCA-2010

Titan is the biggest satellite of Saturne (about half the Earth). Its dense atmosphere of 1.5 bar at the surface is mainly composed of nitrogen and methane. So Titan is considered as an interesting analog of a frozen primitive Earth. Despite the very low temperature, between 100 and 200 K, atmospheric layers undergo efficient reaction chains, initiated by the solar flux and the Saturn magnetospheric electrons. Complex organic matter made of nitrogenated hydrocarbons is produced into the gaseous phase leading to a brownish photochemical fog surrounding the whole satellite.

Several techniques have been developed to simulate lab analogs, called tholins, of Titan’s haze. Most efficient methods presently known involve plasma techniques. Such a plasma device, named PAMPRE, has been developed in LATMOS, using a RF plasma discharge (13.6 MHz) in a stationary flux of nitrogen and methane gaz mixture, at various temperature and pressure conditions. Recent results will be presented concerning in situ mass spectrometry analysis of the gaseous phase and ex-situ chemical and morphological analysis of the tholins.

TUESDAY, March 2, 2010

Dry powder formulation development for nasal vaccination

Regina Westmeier, Department of Pharmaceutics and Biopharmaceutics, Christian Albrecht University, Kiel, Germany

Abstract

I will briefly talk about some aspects of the mucosal immune system, which are important for the nasal vaccination strategy. I will then focus on the nose as delivery location, introduce a nasal cast model for the determination of formulation deposition in the different parts of the nose and show some delivery devices I have been characterizing. Further on I will shortly review the vaccine delivery systems described in literature and will then talk about our formulation strategies. Besides I will introduce a rapid in vitro test to assess the respiratory toxicity of both excipients and complete formulations.

TUESDAY, February 16, 2010

Observations of iodine oxide and reactive gaseous mercury at a coastal site in Pensacola, FL

Sean Coburn

Abstract

An increasing body of evidence suggests that atmospheric halogens, marked largely by the presence of BrO and IO, are ubiquitous components of the lower troposphere in coastal and oceanic areas. The role of halogen chemistry in mercury oxidation in coastal regions remains unknown. Simulations of atmospheric mercury oxidation suggest that chemistry initiated by atomic Br may have been underestimated. Synergistic effects of the iodine compounds can be expected and little is known about the possible direct role I atoms may play to oxidize mercury. Finally, other reactive trace gases, such as CH2O and C2H2O2, can suppress the oxidation of Hg by converting bromine-radicals into chemically inert reservoir species. Here we present data from several months of MAX-DOAS measurements of halogen oxides, O4, CH2O and C2H2O2 in parallel with measurements of speciated mercury (Hg0, Hg2+) that are currently being conducted along the U.S. Gulf Coast.

TUESDAY, February 9, 2010

Light Emitting Diode Cavity Enhanced Differential Optical Absorption Spectroscopy (LED-CE-DOAS): a novel technique for monitoring atmospheric trace gases

Ryan Thalman and Rainer Volkamer

Abstract

The combination of Cavity Enhanced Absorption Spectroscopy (CEAS) with broad-band light sources (e.g. Light-Emitting Diodes, LEDs) lends itself to the application of cavity enhanced DOAS (CE-DOAS) to perform sensitive and selective point measurements of multiple trace gases with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e., does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0) and is therefore insensitive to lamp drifts and/or the presence of aerosols. We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420-490nm) to measure nitrogen dioxide (NO2), glyoxal (CHOCHO), methylglyoxal (CH3COCHO), iodine monoxide (IO), water (H2O) and oxygen dimers (O4). Aerosol extinction is retrieved at two wavelengths by means of observing water and O4 and measuring pressure, temperature and relative humidity independently. The instrument components are presented, and the approach to measure aerosol extinction is demonstrated by means of a set of experiments where laboratory generated monodisperse aerosols are added to the cavity. The aerosol extinction cross section agrees well with Mie calculations, demonstrating that our setup enables measurements of the above gases in open cavity mode.

TUESDAY, February 2, 2010

Environmental Analysis of Water and Food Samples by Advanced Mass Spectrometry Techniques

Imma Ferrer and E. Michael Thurman
Environmental, Civil, and Architectural Engineering
CU, Boulder

Abstract

The analysis of pharmaceuticals and pesticides in water and food is one of the hot topics in environmental analysis. Recently the Associated Press published an article that much of the drinking water of the US is affected by pharmaceuticals coming from our wastewater. This article was backed up by numerous scientific studies since the late 1990s showing pharmaceuticals occurring in surface waters of the US. We have established a Laboratory for Environmental Mass Spectrometry soon to be a Center for Environmental Mass Spectrometry that uses an array of state of the art MS, including LC/time-of-flight MS, triple quadrupole MS with Jetspray, LC/MS ion trap, and other instrumentation to examine questions such as pharmaceuticals in drinking water and pesticides in food. Our seminar will discuss our new Center of Environmental MS, instrumentation, and applications to pharmaceuticals in drinking water and pesticides in food.

FRIDAY, January 22, 2010 (note special day)

Pedro Campuzano-Jost
University of British Columbia, Canada

CIRES Auditorium @ 4:00 p.m University of Colorado, Boulder

Abstract

Trapping organic aerosol ions for molecular identification: Some lessons learned

The incapability of off-line techniques to resolve a significant part of the organic fraction of atmospheric aerosols has resulted in a stronger focus in recent years on developing real time aerosol mass spectrometers that are able to identify not just compound classes, but specific molecules. The approach chosen in most cases has been reducing fragmentation by use of soft-ionization techniques. While use of soft ionization can greatly simplify the mass spectra of complex mixtures, it also tends to erase the chemical information provided by the fragmentation pattern. Therefore, the ability to isolate and obtain tandem MS spectra of individual molecular ions is key to be able to id individual compounds.

Ion traps are compact, versatile devices that are similarly well suited for use in single particle mass spectrometers (SP-MS) than the more ubiquitous reflectron time-of-flight-MS; however, unlike reTOFs, they can also be used for tandem MS experiments. We have recently build a single particle ion trap mass spectrometer (SPIT-MS) that combines in-trap IR laser desorption of particles with a state-of-the-art laser based tabletop tunable VUV source. This allows separate optimization of both the desorption and ionization step for minimal fragmentation and -at high enough IR fluencies- a quantitative response. At the same time, measurements of the first ionization energy of the molecular ion together with their tandem MS spectrum can be used for molecular identification.While the SPIT-MS works as intended with certain types of test aerosol, it mostly fails with mixtures of aliphatic compounds, its intended target. The reasons for this failure will be examined in detail and some of its implications for alternative designs discussed.

In the second part of the talk, two other simpler SPIT-MS designs recently developed at UBC will be discussed:

- A laboratory prototype that uses pulsed IR laser desorption and conventional pulsed 70 eV electron impact for ionization. While its overall performance is comparable to the Aerodyne TOF in single particle mode, in addition it allows for analysis of refractory material as well as tandem MS analysis of larger ions.

- A new field capable ITMS that combines a novel aerosol beam alignment design with a mass spectrometer with dual polarity detection. Ionization occurs by laser ablation at 266 nm. This instrument is currently being deployed to the top of Whistler Mountain, BC to study long range transport of Asian dust.

MONDAY, November 30, 2009

4:00 p.m. CIRES Auditorium University of Colorado, Boulder

Synthesis of Catalyst Arrays from Nanoparticle Precursors

Bryan Tienes

Abstract

The desire to develop novel, more efficient heterogeneous catalysts is a vital area of research in renewable energy applications. Due to the huge compositional and structural parameter space under which solid state materials can exist, it is nearly impossible to develop new heterogeneous catalysts a-priori. Therefore, many research groups have turned to combinatorial methods to identify new materials. While methods of synthesizing combinatorial arrays of bulk materials are well established, combinatorial arrays of nano-materials have been more elusive. Here we present a novel synthesis methodology for arrays of nanoparticles on solid supports using nanoparticles as synthetic precursors. The combinatorial arrays are generated by utilizing multidirectional nanoparticle gradients created by exploiting the kinetics of electrostatic adhesion of nanoparticles to a solid support. Subsequent reaction of the solid supports at elevated temperatures causes adjacent particles to alloy yielding nanoparticles with a gradient of compositions. These reactions have been demonstrated to take place on solid supports in both gaseous and liquid environments. Nanoparticle arrays adsorbed onto indium tin oxide (ITO) coated glass have been shown to alloy in a similar fashion. The arrays on ITO glass were subsequently fabricated into working electrodes for an electrochemical cell. The electrodes were then demonstrated as a catalyst screening tool for methanol fuel cell catalysts.

MONDAY, November 2, 2009

4:00 p.m. CIRES Auditorium University of Colorado, Boulder

A Novel Method for Analysis of Respirable Particle Size Distributions using an Andersen Cascade Impactor

Lia Rebits

Andersen cascade impactors (ACIs) are widely used throughout the pharmaceutical industry to obtain aerodynamic particle size distributions for inhalable products. An ACI separates aerosolized particles by passing them through a series of orifice‐containing stages and plates; the plate on which a certain particle will deposit depends on its velocity and aerodynamic diameter. A limitation encountered with the use of this instrument is that the analytical method chosen to quantify the deposition of particles on each plate must be precise, accurate, and have a low detection limit. A method that measures the total organic carbon (TOC) content on each plate has been found to fulfill many of the requirements needed to obtain accurate particle size distributions.

Amperometric S-Nitrosothiol Sensors: Applications and Methods

Candice Smith

It has been discovered that the right amount of S-nitrosothiol (RSNO) species in blood prevents the activation of clotting agents. A new RSNO detection technique, based on an electrochemical sensor, rapidly measures the level of RSNOs in whole blood. Use of this S-nitrosothiol sensor during surgical procedures, like Extra Corporeal Life Support (ECLS), could provide physicians with a novel method of monitoring a patient’s health. This seminar is an opportunity to describe the methods of the S-nitrosothiol biosensor’s assembly and in vivo testing.

MONDAY, October 26, 2009

4:00 p.m. CIRES Auditorium University of Colorado, Boulder

Practical Analytical Chemistry - Colorimetric Wet Chemistry Methods for Wastewater, Drinking Water, and Natural Water

Kristin Boles

Abstract

Analytical chemistry is an essential tool in drinking water and wastewater regulation. Wet Chemistry specifically refers to analytical chemistry performed in aqueous solution. It is therefore easily performed in the same matrix as wastewater and drinking water. This presentation will cover three wastewater testing methods: EPA 420.1, which tests for all phenols/phenolic compounds; EPA 365.3 dissolved, which tests for the orthophosphate ion in a filtered solution; and SM 3500-Cr B, which tests for hexavalent chromium in natural or treated water. Each of these tests is colorimetric, and the chemistry of their respective color-producing reaction will be discussed, as well as typical matrix interferences.

MONDAY, October 19, 2009

4:00 p.m. CIRES Auditorium University of Colorado, Boulder

Sources of organic aerosols: atmospheric transformations of emissions from combustion systems

Allen Robinson

Carnegie Mellon University

Abstract

Atmospheric particles play an important role in climate forcing; they are also strongly associated with adverse human health effects. Organic aerosols account for a large fraction of ambient fine particle mass, but their sources and transformation processes are still poorly understood. Motor vehicles, wood stoves, and other combustion systems are major sources of organic aerosols. This talk discusses recent field, laboratory, and modeling results on organic particle emissions from combustion systems. The results reveal a dynamic picture in which low-volatility organics evaporate, oxidize, and recondense as they are transported away from the source. This new picture alters our understanding of the contribution of combustion sources to urban and regional pollution and brings chemical transport model predictions into better agreement with field observations. The talk concludes with a discussion of the implications of these recent findings on human exposures and the design of regulations to control organic aerosols.

MONDAY, October 12, 2009

4:00 p.m. CIRES Auditorium University of Colorado, Boulder

New Insights Into the Mechanism of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase

Gregory Schill

Abstract

Class II 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate limiting enzyme of the mevalonate pathway, represents an attractive potential target for the development of antibiotics the against multiple drug-resistant strains of Gram-positive cocci. However, recent steady-state spectrofluorimetric studies suggest that the mechanism of catalysis does not go through a mevaldehyde intermediate as accepted in the literature. The objective of this study was to investigate HMG-CoA reductase catalysis prior to steady-state conditions to determine if this incongruence was the result of a fast equilibrium. Stopped-flow kinetic assays, with dead times of 8 ms, were conducted to probe for the elusive mevaldehyde intermediate. Results found that a fast equilibrium can not account for the absence of mevaldehyde, suggesting a revision of the current literature-accepted mechanism of catalysis to one where coenzyme A plays a more integral role.

A NEGATIVE ION PHOTOELECTRON SPECTROSCOPIC STUDY OF Mo2-.

Sunil Baidar

Abstract

The homonuclear diatomic metal ion Mo2- was studied using negative ion photoelectron spectroscopy. This bare, homonuclear group 6 transition metal dimer allows the study of multiple metal-metal bonding free of ligand effects. The photoelectron spectra, obtained at 488 nm with an instrumental resolution of about 6 meV (50 cm-1), provide measurements of the electron affinities, vibrational frequencies for both the anion and the neutral states, and bond length changes upon electron detachment. The Mo2- spectra displays a transition to the multiply-bonded 1Σg+(dπ)4(dδ)4(dσ)2(sσ)2 ground state of the neutral molecule. In the anion, the extra electron occupies the vacant antibonding sσ* orbital, giving a 2Σu+ ground state.

MONDAY, October 5, 2009

4:00 p.m. CIRES Auditorium University of Colorado, Boulder

Aerosols of the Past: Lessons from Saturn’s Moon Titan

Margaret Tolbert

Dept. Chem & Biochem., and CIRES, CU-Boulder

Abstract

An organic haze layer in the upper atmosphere of Titan plays a crucial role in the atmospheric composition and climate of that moon. Photochemistry in the atmosphere of the early Earth shortly after the time of planetary formation may have led to a similar haze. However, due to differences in atmospheric chemistry, the aerosols formed on the early Earth may have had distinct chemical and optical properties from those suspected to make up the hazes on Titan. We have conducted laboratory experiments simulating photochemical haze production on Titan and early Earth. The resulting aerosols are analyzed using an Aerosol Mass Spectrometer (AMS) to obtain compositional information and extinction cavity ring down (CRD) spectroscopy to determine the optical properties of the particles. The hazes on the two worlds will be compared and the implications of haze on the climate and habitability of ancient Earth will be discussed.

What have we learned about organic aerosol sources and processing? What’s next?

Jose-Luis Jimenez

Dept. Chem & Biochem., and CIRES, CU-Boulder

Abstract

Aerosols play major roles in climate forcing and the hydrological cycle, and also on human health effects, visibility degradation, and deposition of acids, toxics, and nutrients to ecosystems. Organic aerosols (OA) account for a large fraction (~50%) of ambient submicron aerosol mass, but their sources and transformation processes are still poorly understood. I will summarize recent findings about the sources, processing and budget of OA arising from multiple field and lab studies, as well as comparisons to 1D and 3D models. OA from all sources evolves in the atmosphere by becoming more oxygenated and hygroscopic and less volatile, and partially losing the chemical signature of the original source and gaining a common signature of atmospheric oxidation. Secondary OA (SOA) formation in urban areas is greatly underestimated by traditional models, in contrast with biogenic SOA formed under pristine conditions which is reasonably predicted. New models close the gap and even exceed the observed SOA in urban areas, but it is not clear whether this is for the right reasons. Further progress necessitates more complete high-quality measurements at one location as well as new measurement & analysis techniques, and we are preparing for two such campaigns in Los Angeles, CA in 2010 and Manitou Springs, CO in 2011.

MONDAY, September 28, 2009

4:00 p.m. CIRES Auditorium University of Colorado, Boulder

Water and photon mediated chemistry relevant to atmospheric aerosol formation

Veronica Vaida

Dept. Chem & Biochem., and CIRES, CU-Boulder

Abstract

Research in the Vaida group explores the interface between physical chemistry and atmospheric science using tools of spectroscopy, photochemistry and photoreaction dynamics. This presentation will exemplify discuss water catalyzed photochemical reactions of oxidized organic species (acids, alcohols, aldehydes and ketones) relevant to atmospheric chemistry. Our approach utilizes electronic and vibrational spectroscopy to explore chemical reactions. Theoretical modeling in collaboration with the skodje group elucidates the roles of cluster conformation and dynamical effects in the photochemical processes. The specific example of methyl glyoxal, and pyruvic and glyoxilic acids and of their hydrates will be presented. The discussion will point to the role of water and photon mediated chemistry of organic molecules to the generation and processing of secondary organic aerosols and, more generally, to climate.

Instrument development for use in field and laboratory experiments in the ATMOSpeclab

Rainer Volkamer

Dept. Chem & Biochem., and CIRES, CU-Boulder

Abstract

The Atmospheric Trace Molecule Spectroscopy Laboratory (ATMOSpeclab) was established in 2007 at CU Boulder to develop and apply optical spectroscopic instruments to measure atmospheric composition of reactive trace gases in polluted urban, and pristine natural atmospheric environments. Specific atmospheric chemistry projects in the ATMOSpeclab will be discussed, and include: - Impact of halogen chemistry on Mercury deposition in the coastal environment - Airborne MAX-DOAS from research aircraft - Ship based MAX-DOAS in the Southern Hemisphere Pacific Ocean - Laboratory studies of SOA formation from glyoxal in simulation chambers - Development of a detailed model to represent SOA formation via the aerosol aqueous phase

MONDAY, September 21, 2009

4:00 p.m. CIRES Auditorium University of Colorado, Boulder

CU Inhalable Dry Powder Vaccines have Provided Protection Against Infection

R. Sievers, S. Cape, J. Burger, D. McAdams, J. Manion, L. Rebits, S. Winston, B. Quinn, J. Searles, D. Krank, P. Bhagwat, P. Pathak, A. Genosar, R. Dhere, V. Vaidya, R. Muley, D. Griffin, W-H Lin, and P. Rota

Abstract

Protection against infection with measles virus has been demonstrated in animal models immunized 14 months earlier by inhalation of CU-invented dry powder vaccine microparticles. Needle-free aerosol delivery of dry powder vaccines may provide an effective and low-cost means of immunization. Powder manufacturing with gentle, rapid drying by Carbon Dioxide Assisted Nebulization with a Bubble Dryer (CAN-BD) appears to be an attractive alternative to freeze drying of sensitive biologicals like live attenuated Edmonston-Zagreb measles virus vaccine. Stability of measles virus in glassy, dry, respirable microparticles made by CAN-BD with less than 1% water sealed in unidose aluminum foil has been demonstrated. The dry powder aggregate, upon dispersion from an active dry powder inhaler, deposits in the moist respiratory tract where the microparticles rapidly dissolve within minutes. Antibiotics are also being studied and delivered as microparticles against infectious diseases.

Funded by FNIH Grant 1077.

Improving the Performance of Li Ion Batteries Using Atomic Layer Deposition

Steven M. George

Depts. of Chemistry and Chemical Engineering University of Colorado, Boulder, CO 80309 Steven.George@Colorado.Edu

Abstract

Lithium ion batteries (LIBs) are emerging as the dominant power source for portable electronics. Improvement in their capacity lifetime during charge-discharge cycles must be achieved before LIBs can be used for plug-in-hybrid and electric vehicles. LiCoO2 and graphite are common cathode and anode materials, respectively, for LIBs. The capacity loss of LIBs is linked to electrode deterioration caused by interfacial reactions with the electrolyte, dissolution of the metal oxide cathodes and structural instabilities caused by volume expansion during lithium intercalation. Atomic layer deposition (ALD) is based on the strategy of sequential, self-limiting surface reactions to deposit inorganic materials. ALD can deposit thin, conformal films on cathode and anode materials in LIBs to provide chemical protection, restrict dissolution and stabilize structural changes. Our recent work has demonstrated that ultrathin Al2O3 ALD films can improve the capacity stability of LiCoO2 cathodes and graphite anodes. Additional work is developing new protective coatings that will serve as an artificial solid-electrolyte interphase (SEI) for further stability improvement.

MONDAY, September 14, 2009

4:00 p.m. CIRES Auditorium University of Colorado, Boulder

Renewable and Sustainable Energy Institute (RASEI): What does this mean for the Dept. of Chemistry and Biochemistry (and other departments and institutes)?

Carl A. Koval, Co-Director

Abstract

In June 2009, the University of Colorado’s Board of Regents approved the formation of a new campus institute: RASEI (pronounced ‘racy”). This formation of this institute grew out of the former CU-Boulder Energy Initiative (EI), which was created in early 2006. In addition, administrators at CU-Boulder and the National Renewable Energy Laboratory (NREL) in Golden signed a MOU to operate RASEI as a joint institute. In this presentation, I will focus on:

• the transition of the EI to RASEI, from initiative to institute;

• opportunities for faculty to be involved in RASEI governance and programs;

• opportunities for students to be involved RASEI’s research, teaching, commercialization and outreach activities.

For more information about RASEI, go to http://rasei.colorado.edu.

Research at the Interface of Nanoscale Materials and Biology

Daniel L. Feldheim

Dept. Chem & Biochem., CU-Boulder

Abstract

Between the size scale of individual biomacromolecules and cellular organelles lies a size regime―the few nm to 100 nm range―that is not readily probed using existing technologies. Thus, while a vast inventory of RNA and protein sequences and structures are being catalogued, a quantitative cellular context for these structures is lagging. Yet to understand this context would be to know how collections of individual macromolecules assemble into the dynamic machines that form a living cell. Once these interactions are revealed, a new picture of the cell and its disease states is sure to emerge.

With achievable 2 nm resolution and perfect preservation of cellular structure, electron tomography (ET) now represents the highest resolution technique for examining biomolecules in their native cellular context. Indeed, cell biologists now dream of generating 3D images containing the entire proteome of a living cell. This dream remains out of reach, not because ET cannot visualize individual proteins, but because it is simply not possible currently to know which protein is which in a tomographic cellular reconstruction.

This presentation will describe methods being developed in our lab for creating electron dense nanoparticle tags for identifying cellular biomolecules by ET. These methods rely on the discovery of materials ribozymes and enzymes―RNA and protein/peptide sequences that can catalyze the formation of inorganic nanoparticles and control nanoparticle growth. The isolation and structure-function relationships of a number of materials ribozymes and enzymes will be shown.

In addition to visualizing biomolecule interactions in cells, we are working on ways to mimic and disrupt such interactions for disease treatment. We view this largely as a materials problem as well, and have been learning how to design metal nanoclusters to effectively interact with cellular biomolecules. A few lessons learned in our studies of cell and nuclear targeting and the prevention of viral infection will be described.

THURSDAY, September 10, 2009

4:00 p.m. CIRES Auditorium (note change of location) University of Colorado, Boulder

What controls the diurnal variability of carbon dioxide and reactive species? (a.k.a. "Boundary Layers for Chemists")

Jordi Vilà-Guerau de Arellano
Meteorology and Air Quality Section
Wageningen University (The Netherlands)
e-mail: jordi.vila@wur.nl

Abstract

We examine the main physical and chemical processes that determine the diurnal variability of atmospheric compounds in the boundary layer. In addition to surface processes, turbulent mixing and reactivity, we put special emphasis on investigating the role of the exchange of heat, water and chemical species between the free troposphere and the atmospheric boundary layer, namely the entrainment process. This process enhances the dilution of compounds and introduces free tropospheric air masses with different characteristics into the atmospheric boundary layer.

In the seminar, I will discuss several cases where entrainment plays a major role in the evolution of atmospheric compounds. By analyzing observational evidence or performing numerical experiments by the large eddy simulation technique and a conceptual (mixed-layer theory) model, we are able to find the contribution of entrainment to the diurnal variability of carbon dioxide or isoprene. Particular emphasis is placed on the need to maintain a balance in dynamic processes and the specific characteristic of each atmospheric compound.