Presentation on theme: "Evaluation of Alternative Methods for the Quantification of Carbonyl and Polycyclic Aromatic Hydrocarbon (PAH) Concentrations in Ambient Air Broward County."— Presentation transcript:
Evaluation of Alternative Methods for the Quantification of Carbonyl and Polycyclic Aromatic Hydrocarbon (PAH) Concentrations in Ambient Air Broward County Pollution Prevention, Remediation, and Air Quality Program Lead Investigator: Ana E. Suarez, Ph.D. Presenter: Monica Pognon, Ambient Air Monitoring Section Manager
Test alternative methods Alternative carbonyl method vs. TO-11 Alternative PAH method vs. TO-13 Additionally, analyze the alternative samples for other compounds as suggested by the literature. Carbonyl study alluded to analyzing samples for both VOCs and carbonyls PAH study alluded to analyzing samples for VOCs, PAHs, and PCBs Prepare reports to the U.S. EPA addressing effectiveness of alternative methods. Share results of the study with Federal, State, Local, and Tribal programs through Presentations at conferences Webinars Informational outreach materials Technical documents, i.e., Standard Operating Procedures (SOPs) Quality Assurance Project Plans (QAPPs) Depending on favorable results of study, prepare the Broward County Air Toxics Program to become a central laboratory for alternative method analysis.
Most of the national cancer risk and the non-cancer hazard drivers in the National Air Toxics Assessment (NATA) fall into one of the four main chemical classes analyzed in ambient air by standard U.S. EPA methods
While air toxics chemical classes are monitored throughout the US, chemical classes that require extensive or expensive analysis are monitored less frequently. Example of this distribution of air toxics chemical classes monitored is seen in this Region 4 map from The 2007 Southeastern Air Toxics Data Analysis (STI- 906021.7-3122-FR). The current methods employed to determine concentration of certain pollutants can be cumbersome, complex, or financially impossible for local, state, and tribal programs to undertake. Methods that are economically feasible and practical are necessary to increase the availability of air toxics data. Wider availability of ambient concentration measurements would be invaluable to our understanding of air toxics. Would lead to development of more accurate models. Would allow for easier investigation of hot spots. In Region 4, volatile organic compounds (VOCs) and metal species are monitored extensively, while semi-volatile organic compounds (SVOCs), and carbonyls are monitored by fewer state, local, and tribal agencies.
TO-11 A carefully measured volume of ozone-scrubbed ambient air is drawn through a cartridge of sorbent- coated with 2,4-Dinitrophenylhydrazine (DNPH). In the cartridge, the highly volatile and reactive, carbonyls are converted to stable DNPH-derivatives. Compounds are extracted with solvents and analyzed by high precision liquid chromatography coupled with ultra violet detection (HPLC/UV). TO-13 A high volume ambient air collector (HiVol) is used to pull air through a quartz fiber filter followed by a polyurethane foam plug (PUF) and/or XAD media in order to collect particulate and gas phase PAHs. Both phases undergo a solvent extraction procedure to remove PAHs from the collection media. The PAHs dissolved in organic solvents are evaporated to reduce volume size. A portion of the total remaining volume (roughly 1/10 th ) is injected into a GC/MS for analysis. Disadvantages Both require complex methods to prepare the sample for analysis. Both require solvent extraction. Can lead to sample losses due to the sample handling and manipulation required. Methods are involved, requiring significant amounts of time to process the sample for analysis. As a result, expedited results are unlikely or impossible. Often costly, due to the amount of equipment and consumables required to perform the extractions. Outsourcing of these analysis can be as expensive as performing them in-house. A lot of waste products (chemical solvents) created as a result of the extractions.
Title Study: Formaldehyde and VOCs in Indoor Air Quality Determinations by GCMS Study Authors: Dan Cardin and Tom Robinson, Entech Instruments, Inc., Simi Valley, CA 93065 Study Summary: Air samples are collected in silonite coated canisters with silonite coated tubing which prevents the wall-losses of volatile carbonyls. Samples are analyzed directly from the canisters by GC/MS with carbonyl standards using a preliminary preconcentration step to improve method sensitivity along with the silonite coated internal lines present in the Entech 7100 preconcentrator. The study was performed on indoor air, but the authors mention that it can be used for ambient air as well. Additional Benefit: The authors mention that VOCs and carbonyls can be determined from a single collected sample.
Title Study: Improved accuracy in the determination of polycyclic aromatic hydrocarbons in air using 24h sampling on a mixed bed followed by thermal desorption capillary gas chromatography – mass spectrometry Study Authors: Eric Wauters, Peter Van Caeter, Gilbert Desmet, Flemish Environmental Agency, Krijgslaan, 281-S2, B-9000 Gent, Belgium and Frank David, Christophe Devos, Pat Sandra, Research Institute for Chromatography, Pres. Kennedypark 26, B-8500 Kortrijk, Belgium Citation: Journal of Chromatography A, 1190 (2008), 286-293 Study Summary: Both high and low boiling point PAHs, including naphthalene, were collected at a low flow rate (100 mL/min) using a personal air sampling pump and commercially available thermal desorption (TD) tube packed with a novel mixed bed sorbent comprised of polydimethylsiloxane (PDMS) and TENAX TA (porous polymer resin based on 2,6-disphenylene oxide) particles with PDMS foam plug. Samples were analyzed directly off the TD tubes by thermal desorption (TD)-GC/MS with no chemical extraction. This method was tested against the standard TO-13 method. Study results indicate that ambient PAH concentrations (both particle and gas phase) recovered by the TD tube were generally greater than those determined by the TO-13 Method. This was especially true for the low boiling point PAHs (i.e., naphthalene and acenaphtene). Most of the other PAHs measured were within a factor of two. Additional Benefit: The authors mention that VOCs, PAHs, and PCB concentrations could be determined from a single sample.
Carbonyls Site: #34 NCORE Site Siting Logic: Inclusion among suite of air sampling data Sampling Frequency: 1-in-6 days following UATMP schedule. Equipment: Traditional: Carbonyl DNPH Sampler Alternative: silonite coated canister, tubing, and timer Analysis: Traditional: Extraction followed by HPLC-UV Alternative: GC-MS PAHs Site: #25 John U. Lloyd State Park (adjacent to Port Everglades) Siting Logic: Ensure likelihood of greatest PAHs at chosen site. Sampling Frequency: 1-in-6 days following UATMP schedule. Equipment: Traditional: HiVol with PAH quartz and PUF/XAD media Alternative: Personal sampler pump with TD tubes filled with PDMS /TENAX TA resins and a PDMS plug Analysis: Traditional: Extraction followed GC-MS Alternative: TD-GC-MS All equipment will involve an inlet to prevent rain from entering the sample. Alternative methods will be run in replicate to test sampling precision. 34 NCORE
Progress Reports A final report detailing project implementation, data comparison of alternative and standard methods, analysis of feasibility of alternative methods (i.e., ease of establishment, cost analysis, nuances, notes, providers of equipment or supplies that are not common, etc.) Presentation of study results at U.S. EPA national or regional conference(s) and Webinar(s) Publicly available air toxics data in central repository (U.S. EPA AQS) – carbonyls by TO-11 & PAHs by TO-13 Contingent upon acceptance of Alternative Methods by the U.S. EPA Outreach material informing air agencies of the availability of alternative methods for PAHs and carbonyls with a brief discussion of the methods. Technical documents explaining the sampling/analysis in detail (i.e., SOP and QAPP for each of the alternative methods). Publicly available alternative carbonyl and PAH air toxics data in central repository (U.S. EPA AQS). Analysis services for alternative methods provided by the Broward County Air Toxics Laboratory
Evaluation of these methods by a local air monitoring program would test not only how well the methods work, but how feasible they would be to enact for local, state, and tribal air monitoring programs as alternatives to standard methods TO-11 and TO-13. If these methods are as easy and affordable to enact as they appear to be from the literature, they could increase the monitoring of these air toxics throughout the U.S., thus enabling agencies to Fill in spatial and temporal data gaps in ambient air toxics concentrations Test impacts of local sources, Monitor effectiveness of pollution reduction strategies Perform trends analyses Perform model-to-monitor comparisons for model validation Allow for monitoring of problem pollutants and mitigation efforts that may have previously been out of reach of the financial and technical means of an area