Modeling solid-phase microextraction of volatile organic compounds by porous coatings using finite element analysis

Experimental optimization of analytical methods based on solid-phase microextraction (SPME) is a complex and labor-intensive process associated with uncertainties. Using the theoretical basics of SPME and finite element analysis software for the optimization proved to be an efficient alternative. In this study, an improved finite element analysis-based model for SPME of volatile organic compounds (VOCs) by porous coatings was developed mainly focussing on the mass transport in coatings. Benzene and the Carboxen/polydimethylsiloxane (Car/PDMS) coating were used as the model VOC and a porous SPME coating, respectively. It has been established that in the coating, volumetric fractions of Carboxen, PDMS, and air are 33, 42 and 24%, respectively. Knudsen diffusion in micropores can slow down a mass transport of analytes in the coating. When PDMS was considered as the solid part of the coating, lower root-mean-square deviation of the modeling results from experimental data was observed. It has been shown that the developed model can be used to model the extraction of VOCs from air and water samples encountered in a typical SPME development method procedure. It was possible to determine system equilibration times and use them to optimize sample volume and Henry\u27s law constant. The developed model is relatively simple, fast, and can be recommended for optimization of extraction parameters for other analytes and SPME coatings. The diffusivity of analytes in a coating is an important property needed for improved characterization of existing and new SPME polymers and analytical method optimization

Characterization of Livestock Odors Using Steel Plates, Solid Phase Microextraction, and Multidimensional-Gas Chromatography-Mass Spectrometry-Olfactometry

Livestock odor characterization is one of the most challenging analytical tasks. This is because odor-causing gases are often present at very low concentrations in a complex matrix of less important or irrelevant gases. The objective of this project was to develop a set of characteristic reference odors from a swine barn in Iowa, and in the process identify compounds causing characteristic swine odor. Odor samples were collected using a novel sampling methodology consisting of clean steel plates exposed inside and around the swine barn for up to one week. Steel plates were then transported to the laboratory and stored in clean jars. Headspace solid phase microextraction (SPME) was used to extract characteristic odorants collected on the plates. All analyses were conducted on a Gas Chromatography-Mass Spectrometry (GC-MS)-Olfactometry system where the human nose is used as a detector simultaneously with chemical analysis via MS. The effects of sampling time, distance from a source, and the presence of particulate matter (PM) on the abundance of specific gases, odor intensity, and odor character were tested. Steel plates were effectively able to collect key volatile compounds and odorants. The abundance of specific gases and odor was amplified when plates collected PM. The results of this research indicate that PM is major carrier of odor and several key swine odorants. Three odor panelists were consistent in identifying p-cresol as closely resembling characteristic swine odor as well as attributing the largest odor response out of the samples to p-cresol. Further research is warranted to determine how the control of PM emissions from swine housing could affect odor emissions

Agriculture Study Abroad program to Poland

The Technology Travel Course (TSM 496) is an elective course that meets the university-wide international perspectives requirement. The course has a curricular home in the department of Agricultural and Biosystems Engineering (ABE), Iowa State University (ISU). It enables instructors to develop and offer a study abroad program structured as a faculty-led trip abroad. This course is also an excellent opportunity for students to learn/compare technology concepts and applications in an international context that is encouraged by the ABE External Advisory Board. The objectives of this paper are to (1) Review the application of TSM 496 to Ag Study Abroad trip to Poland (with cultural trips to Czech Republic, Denmark, Germany, Lithuania, and Ukraine, and to (2) summarize curricular enhancement of student learning objectives (SLOs) and competencies. The course has been offered yearly since 2011, and served 48 students from several majors in Agriculture & Life Sciences and Engineering colleges. The pre-departure course is focused on teaming up ISU students with students at two agricultural universities in Poland. Teams develop comparative projects focused on agriculture with specific emphasis on animal systems production, technology, environment, sustainability, and regulations. Projects are finalized and presented jointly at special Polish-American Student Workshops. The joint project format creates an opportunity to make friends with students in Poland while working on international projects. The scientific part of the program is a mix of field trips to farms, plants, co-ops, lab tours, cultural sites and activities. Students have many opportunities to socialize, get inspired by rich culture, history, science, agro business attitudes and the spirit of change. SLOs are measured with the program surveys. Currently 65 SLOs/competencies are enhanced with 17 provided by this program (26%). In addition, 25 new competencies are gained, a 38% increase to the new total of 90. Students highly rate this learning and often list it as a highlight of their college career thus far. Data analysis of the Program Evaluation Surveys shows high degree of developing student skills, meeting and enhancement of class goals, departmental and college SLOs

Perspectives and challenges of on-site quantification of organic pollutants in soils using solid-phase microextraction

This study explores the current state-of-the-art progress toward on-site quantification of organic pollutants in soils with solid-phase microextraction (SPME). In spite of many available methods, only few publications report on-site analyses of soil samples by SPME. To date, the only application of SPME for the on-site quantification of organic pollutants in soil has been devoted to trichloroethylene. The problem of matrix effects limiting quantification by external standard calibration is discussed. Efficiencies of available approaches for decreasing and controlling matrix effects are evaluated and compared. SPME from a soil sample headspace with internal standard calibration was identified as one of the promising approaches to achieve fast, simple, precise, and accurate on-site quantification of a wide range of organic pollutants in soil. Cold-fiber SPME has a significant development potential, because it is capable of providing lowest detection limits together with a minimum matrix effect. Perspectives for future development of the field are outlined

Test Device and Process for Assessment of Smithfield Facility Aging

● Establishing structural objective tests and recommendations for hog production facilities. ● The risks are to the livestock, growers, and Smithfield for potential collapses of hog facilities in NW Iowa. ● We assess our solution to be applicable to a large portion of the hog production industry to quickly and objectively measure truss deterioration and provide detailed monetary and structural guidance to growers

2017 update - Air Quality Laboratory & Olfactometry Laboratory Equipment - Koziel\u27s Lab

EQUIPMENT Major equipment in Dr. Koziel’s laboratory ([email protected]) see reference list below for complete descriptions of equipment used in previous research. For odorous VOC gas quantification: VOCs: Agilent 6890 GC-MS-FID-PID (5975C) VOCs: multidimensional GC-MS-Olfactometry (based on Agilent GC-MS platform) equipped with thermal desorption for sorbent tubes. NH3 and H2S (Drager electrochemical portable meter). INNOVA (NH3, CO2) Greenhouse gas GC-FID-ECD (for CO2, CH4, and N2O

Water–Energy–Food Nexus Framework for Promoting Regional Integration in Central Asia

This paper focuses on regional integration through the lenses of the Water–Food–Energy (WEF) nexus, a concept putting strong emphasis on cross-sectoral and multi-level interactions as well as on resource interdependencies. There is an extensive amount of published research focusing on the Aral Sea basin. In this paper, the authors build upon these different contributions and provide a meta-analysis of the literature of WEF nexus opportunities in Central Asia (CA) countries. This paper contributes to ongoing discussions regarding how the WEF Nexus can represent an opportunity for reinforced collaboration regarding resources management. To do so, focusing on existing literature, this paper first (1) explores how the nexus can be a relevant instrument for regional integration. Second (2), it provides an overview of water, food, energy conditions and challenges in the Aral Sea basin in particular. Third (3), synthesizing existing research, the authors identify critical variables to be considered as hurdles or leverage points for WEF nexus implementation in the Aral Sea basin. Finally (4), we go back to our initial set of questions and identify some possible avenues for future research

Assessment of a Two-Stage Wood Chip-Based Biofilter Using Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry-Olfactometry

A mobile pilot-scale biofilter testing laboratory, which consisted of one- and two-stage biofilter reactor barrels, was developed where two types of wood chips (western cedar and hard wood) were examined to treat odor emissions from a deep-pit swine finishing facility in central Iowa. The biofilters were operated continuously from July 20 to October 17, 2007 at differe nt air flow rates resulting in variable empty bed residence times. During this test period, solid-phase microextraction 85 µm Carboxen/PDMS fibers were used to extract volatile organic compounds (VOCs) from both the control plenum and biofilter treatment. Analyses of VOCs were carried out using a multidimensional gas chromatography-mass spectrometry-olfactometry system. Reductions of nine odorous compounds were reported. An overall average reduction efficiency of 98.9% and 96.4% was achieved for two-stage western cedar and hardwood biofilters, respectively. The results showed that maintaining proper moisture content is critical to the success of wood chip-based biofilter

Quantification of BTEX in Soil by Headspace SPME–GC–MS Using Combined Standard Addition and Internal Standard Calibration

There is a great demand for simple, fast and accurate methods for quantification of volatile organic contaminants in soil samples. Solid-phase microextraction (SPME) has a huge potential for this purpose, but its application is limited by insufficient accuracy caused by a matrix effect. The aim of this research was to develop the method for BTEX quantification in soil using combined standard addition (SA) and internal standard (IS) calibration. Deuterated benzene (benzene-d6) was used as the internal standard for all analytes. The optimized method includes spiking replicate samples with different concentrations of BTEX standards and the same concentration of benzene-d6, equilibration of soil samples at 40 °C during 2 h, and SPME–GC–MS analysis. Precision and accuracy of IS and SA methods were compared on different soil matrices. Combined SA + IS method provided more precise calibration plots compared to the conventional SA calibration. The SA + IS calibration provided more precise and accurate results compared with a reference method based on solvent extraction followed by GC–MS when applied to BTEX quantification in real soil samples (spiked with diesel fuel and aged). Recoveries of BTEX from soil samples spiked with known concentrations of analytes using the developed method were in the range of 73–130% with RSD values less than 15% for all BTEX. The proposed simultaneous standard addition and internal standard approach can be advantageous and adopted for improved quantification of other toxic VOCs in soil