Grantee Research Project Results
2007 Progress Report: Polar Organic Compounds in Fine Particles from the New York, New Jersey, and Connecticut Regional Airshed
EPA Grant Number: R832165Title: Polar Organic Compounds in Fine Particles from the New York, New Jersey, and Connecticut Regional Airshed
Investigators: Mazurek, Monica
Institution: Rutgers
EPA Project Officer: Chung, Serena
Project Period: January 1, 2005 through December 31, 2007 (Extended to December 31, 2009)
Project Period Covered by this Report: January 1, 2007 through December 31,2007
Project Amount: $449,150
RFA: Source Apportionment of Particulate Matter (2004) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air
Objective:
Fine particles in urban atmospheres are composed of highly complex mixtures of organic compounds spanning large ranges of molecular weight and compound group classifications. However, nearly 50% of the organic carbon mass collected as fine particles cannot be analyzed using current molecular level mass spectrometric analytical methods (e.g., gas chromatography/mass spectrometry, GC/MS) due to low volatility in the gas chromatographic system.
The original objective of the research was to apply liquid chromatography mass spectrometry (LCMS) analysis to extracts of 24-hr fine particle filter samples collected in the metropolitan NY City area. However, the LCMS ion trap instrument we used for the analysis failed to function reliably as a quantitative measurement device. We stopped further work with the LCMS by July 2007. Beginning January 2007, we focused on two alternative analysis methods for highly polar organic compounds: 1) 2,4-dinitrophenylhydrazine (DNPH) derivative formation with high pressure liquid chromatography with a diode array ultraviolet/visible detector (HPLC UV/Vis) for quantitation of carbonyl containing compounds (ketones, aldehydes, oxoacids); and 2) BSTFA derivatization of –OH and –COOH organic compounds to trimethylsilyl (TMS) ether derivatives with gas chromatography mass spectrometry (GCMS) analysis. The two analysis methods were applied to methylene chloride and acetone (1:1) extracts of fine particle samples collected on quartz filters and grouped as seasonal or monthly composites.
The main goals of the revised project were: 1) to identify and measure the ambient abundances of polar organic compounds (acids and bases) found as PM2.5 in the NY, NJ and CT regional airshed using GCMS and HPLC-UV/Vis chemical analyses; 2) to measure and identify both known and potential secondary organic aerosol source markers found within the fine particle acidic organic fraction; and 3) to screen the SOAP filter polar extracts for highly polar molecular markers from primary sources of urban fine particles.
Progress Summary:
Significant new quantitative approaches for polar organic compounds in fine particulate matter (PM) were developed in Year 3 of this project. The analytical methods employ HPLC UV/Vis analysis and GCMS electron impact (EI) analysis with derivatized polar organic compounds.
We devised an efficient HPLC UV/Vis analysis method for atmospheric carbonyl compounds that uses a C8-monolithic silica column. The method is 60% faster than current federal and state standard methods for atmospheric carbonyl compounds as 2,4-DNPH derivatives and uses only one analytical column. Low molecular-weight carbonyl compounds (C7-C14 aldehydes and ketones) were successfully separated and quantified using a novel reverse phase HPLC method employing a C8 monolithic silica column with gradient elution and UV/Vis detection. The method is an improved approach for the routine analysis of volatile carbonyl compounds compared to current standard U.S. EPA HPLC methods for this class of regulated compounds. Given the new U.S. EPA Final Rule for ground-level ozone, increased surveillance will be necessary to monitor emission sources and ambient concentrations of airborne carbonyl compounds as ozone precursors. The monolithic silica column separates carbonyl compounds 60% faster than the current standard methods using multiple packed columns. The improved separation efficiency results in less costly sample analysis and reduces levels of waste mobile phase that must be disposed or incinerated as hazardous waste. This study suggests the need for updating the current federal protocol for airborne carbonyl compounds as DNPH-derivatives. Modern column technology offers clear advantages for efficient separation, precise and quantitative results. A manuscript is nearly completed on this updated analysis method for atmospheric carbonyl compounds.
We developed a novel HPLC UV/Vis quantitative analysis method for oxoacids (e.g., 2-oxo-acetic acid, 2-oxo-propanoic acid, 2-oxo-butanedioic acid, 4-oxo-pentanoic acid, 5-oxo-hexanoic acid) found in atmospheric PM. This suite of oxoacids is thought to originate from photochemical oxidation of volatile or particle-bound organic compound precursors in the atmosphere. The oxoacids were converted to 2,4-DNPH derivatives and were measured by HPLC UV/Vis analysis. The injected mass of the free oxoacids before DNPH derivatization was 10 ng to 1000 ng. All 5 oxoacids tested as DNPH-derivatives had UV/Vis absorption maxima at 365 nm. This coincided with the key wavelength used for quantitation of common low molecular-weight atmospheric aldehydes and ketones screened by federal and state measurement protocols. Because oxoacids are UV-Vis detectable at the same wavelength as the aldehyde and ketone DNPH derivatives, they may interfere with carbonyl analysis through coelution. Retention time and UV/Vis absorption would be inadequate to confirm either peak purity or compound identity. LC-MS would be required to confirm the carbonyl compound DNPH-derivatives. The editor of Separation Science invited us to submit a paper on this novel method to the American Laboratory On-Line special issue, “Advanced Chromatography”. The paper is in press.
We expanded the range of polar organic compounds extracted with a moderately polar extraction mixture (methylene chloride:actone 1:1), derivatized with BSTFA to TMS ethers, and then analyzed by GCMS. Oxoacids and hydroxy acids were studied first as standard suites and were found to produce stable TMS ethers that could be reliably detected and measured by GCMS. These two classes of multifunctional organic compounds are hypothesized to be formed photochemically in the atmosphere. Therefore, monitoring their seasonal and spatial abundances at the urban and rural receptor sites and comparing these results with copollutant concentrations (e.g., ozone, SO2 and NOx) should provide insights into possible molecular surrogates that can track bulk OC from “primary” or “secondary” sources. Five-level calibration curves were generated for the 30 polar organic marker compounds. The linear correlation coefficient (R2) for the calibration curves ranged generally from 0.96 to 0.99, indicating high precision for the BSTFA-derivative and GCMS analysis approach. Given these results, we moved on to the analysis of polar organic compounds in ambient fine particle samples.
We completed chemical analysis of the NY City area fine PM organic fraction that was extracted with the methylene chloride and acetone mixture. Approximately 30 oxoacids, diacids, hydroxyacids, sugars, levoglucosan, n-alkanols, cholesterol, phytosterols, and polyols were converted to the TMS ethers and were analyzed by GCMS. Although, HPLC analysis was possible for the 2,4-DNPH derivatives of the simple aldehydes and ketones and the oxoacids, only GCMS the TMS ethers proved to be the single analytical method suitable for all target compounds. Forty ambient sample composites from the SOAP 2002-2003 (May 2002 to May 2003) field campaign and 20 sample composites from the SOAP-NY (September 2005-Feburary 2007) were evaluated for the polar markers. We completed the ambient concentration calculations and converted the measurements to an EXCEL file for the Chemical Mass Balance (version 8.2) source apportionment model. The modeling effort will be performed as a collaborative project with US EPA NERL scientists and our Rutgers group. Because the fine particle emissions inventory for the metropolitan NY City area has incomplete chemical profiles for major emission sources, additional source profiles from the US EPA NERL emissions repository database will be required to perform the CMB source apportionment modeling for the 2002-2007 NY area fine PM. Data interpretation of the spatial and seasonal trends of the 30 polar markers is in progress. We are comparing the ambient concentrations with co-pollutant data to identify which of the 30 polar markers correlate with primary (SO2 and NOx) and secondary (ozone) gas phase species.
Future Activities:
This project continues as a no-cost extension through December 31, 2008. Research in Year 4 will focus on MS interpretation and data reduction of approximately 50 polar organic target molecular markers in the SOAP fine particle samples (~90 total samples). These marker compounds are indicators of emission sources such as wood smoke, motor vehicles, meat cooking and vegetation. Secondary compounds represented by the hydroxyl acids and oxo acids will be screened also in the SOAP network samples.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 15 publications | 4 publications in selected types | All 4 journal articles |
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Type | Citation | ||
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Hawley HA, Mazurek MA. Oxocarboxylic acids as DNPH derivatives with a monolithic silica column and UV-VIS detection. American Laboratory Online 2008;1(3 Part 2):23-27. |
R832165 (2007) R832165 (2008) R832165 (Final) |
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Supplemental Keywords:
ambient air, atmosphere, sources, particulates, PAHs, organics, analytical, measurement methods, LCMS, northeast, Atlantic coast, midatlantic, New York, NY, New Jersey, NJ, Connecticut, CT, EPA Region 2, polar organic compounds, primary organic carbon, secondary compounds,, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, POLLUTANTS/TOXICS, particulate matter, Air Quality, air toxics, Environmental Chemistry, Chemicals, Air Pollution Effects, Monitoring/Modeling, Environmental Monitoring, Atmospheric Sciences, Engineering, Chemistry, & Physics, Environmental Engineering, particle size, atmospheric particulate matter, health effects, air quality modeling, mass spectrometry, aerosol particles, motor vehicle emissions, human health effects, PM 2.5, wood combustion, atmospheric particles, air quality models, airborne particulate matter, particulate emissions, air modeling, air sampling, gas chromatography, thermal desorption, air quality model, emissions, benzene, particulate matter mass, human exposure, particle phase molecular markers, particle dispersion, aerosol analyzersProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.