Comparison of Sampling Methods for Semi-Volatile Organic Carbon Associated with PM2.5

Lewtas, Joellen; Pang, Yanbo; Booth, Derrick; Reimer, Steve; Eatough, Delbert J.; Gundel, Lara A.

doi:10.1080/027868201300081905

Cited by 17 publications

(24 citation statements)

References 21 publications

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“…With preceding denuders. Lewtas et al [2001] reported 3.0 ± 1.4 μg m −3 of OC on backup XAD‐coated quartz filters and 49 ± 5 μg m −3 on backup CIF filters at Seattle, Washington, during spring 1999. The high backup CIF OC was attributed to contamination from residual solvents used in extracting the denuders between sample runs and released during sampling [ Lewtas et al , 2001].…”

Section: Resultsmentioning

confidence: 99%

“… Lewtas et al [2001] reported 3.0 ± 1.4 μg m −3 of OC on backup XAD‐coated quartz filters and 49 ± 5 μg m −3 on backup CIF filters at Seattle, Washington, during spring 1999. The high backup CIF OC was attributed to contamination from residual solvents used in extracting the denuders between sample runs and released during sampling [ Lewtas et al , 2001]. Fitz [1990] reported that samples preceded by a parallel quartz filter denuder yielded consistently (∼12%) lower OC concentrations than nondenuded samples, with an absolute difference of 2.01 μg m −3 (∼60% to 70% higher than the differences in Table 2).…”

Section: Resultsmentioning

confidence: 99%

“…Differences in sampler flow rates result in different pressure drops across a sampling filter that affect the vapor pressure over volatile substances, resulting in different organic carbon collection [ McDow and Huntzicker , 1990]. Furthermore, different methods to quantify organic carbon (OC) and elemental (or black) carbon (EC) often give different results when applied to the same samples [e.g., Allen et al , 1999; Babich et al , 2000; Birch , 1998; Chow et al , 2001; Guillemin et al , 1997; Hitzenberger et al , 1999; Lewtas et al , 2001; Petzold and Niessner , 1995a, 1995b; Schmid et al , 2001; Turpin et al , 1997], although total carbon (TC) concentrations are usually comparable.…”

Section: Introductionmentioning

confidence: 99%

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Comparison and evaluation of in situ and filter carbon measurements at the Fresno Supersite

Watson

Chow

2002

J. Geophys. Res.

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[1] The Fresno Supersite in Fresno, California, USA, acquires in situ 5-to 60-min average PM 2.5 organic carbon (OC), elemental carbon (EC), and total carbon (TC) measurements by the following methods: (1) thermal evolution carbon analyzer for organic, elemental, and total carbon; (2) single-wavelength and seven-color aethalometer for black carbon (BC); and (3) photoionization for particle-bound polycyclic aromatic hydrocarbons. Twenty-four-hour average PM 2.5 filter-based measurements include (1) nondenuded quartz filters with no backup filter in a PM 2.5 Federal Reference Method (FRM) sampler; (2) quartz filters behind an organic carbon denuder with a quartz backup filter in a Reference Ambient Aerosol Sampler (RAAS); (3) nondenuded quartz filters with backup filter in a RAAS; and (4) nondenuded quartz filters with no backup filter in a sequential filter sampler. Filter samples are analyzed after sampling by the Interagency Monitoring of Protected Visual Environments (IMPROVE) thermal/optical reflectance carbon analysis protocol. Collocated measurements are examined for year 2000. Measurement equivalence is found for PM 2.5 mass, light transmission, and TC between the FRM and RAAS speciation samplers. The average ratios of front filter carbon between the denuded and nondenuded channels in the RAAS sampler are 0.83 ± 0.19 for TC, 0.81 ± 0.20 for OC, and 1.01 ± 0.33 for EC. The average differences for TC and OC are low (1.2 to 1.4 mg m -3 ) and are comparable to the measurement uncertainties. Continuous thermal evolution carbon measurements are not comparable to filter measurements. Aethalometer BC and filter EC are highly correlated, but filter EC is consistently 20-25% higher than continuous aethalometer BC. Pairwise comparisons show filter EC measurements acquired in this study are predictable from aethalometer BC measurements.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison and evaluation of in situ and filter carbon measurements at the Fresno Supersite

Watson

Chow

2002

J. Geophys. Res.

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“…QFFs, CIG, CIF, XAD, and PUF also are used as the adsorbent downstream of the QFF. 5,6,16,23,24 Denuder collection efficiencies for filter-adsorbable organic vapors of 80 -100% have been reported. 5,6,16,23,24 EXPERIMENTAL WORK Objectives The purpose of this paper is to discuss options for artifact correction in large routine sampling networks.…”

Section: Measurement-based Artifact Correction Methodsmentioning

confidence: 98%

“…5,6,16,23,24 Denuder collection efficiencies for filter-adsorbable organic vapors of 80 -100% have been reported. 5,6,16,23,24 EXPERIMENTAL WORK Objectives The purpose of this paper is to discuss options for artifact correction in large routine sampling networks. Specifically, this paper discusses the assumptions and limitations inherent to the RM, compares RM performance with measurement-based methods for a few studies, provides some guidance to those using the RM, describes other approaches to artifact correction, and suggests a strategy for artifact correction in large networks going forward.…”

Section: Measurement-based Artifact Correction Methodsmentioning

confidence: 98%

Correction Methods for Organic Carbon Artifacts When Using Quartz-Fiber Filters in Large Particulate Matter Monitoring Networks: The Regression Method and Other Options

Maimone

Turpin

Solomon

et al. 2011

Journal of the Air & Waste Management Association

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Sampling and handling artifacts can bias filter-based measurements of particulate organic carbon (OC). Several measurement-based methods for OC artifact reduction and/or estimation are currently used in research-grade field studies. OC frequently is not artifact-corrected in large routine sampling networks (e.g., U.S. Environmental Protection Agency (EPA)'s Chemical Speciation Network). In some cases, the OC artifact has been corrected using a regression method (RM) for artifact estimation. In this method, the gamma-intercept of the regression of the OC concentration on the fine particle (PM2.5) mass concentration is taken to be an estimate of the average OC sampling artifact (net of positive and negative artifacts). This paper discusses options for artifact correction in large routine sampling networks. Specifically, the goals are to (1) articulate the assumptions and limitations inherent to the RM, (2) describe other artifact correction approaches, and (3) suggest a cost-effective method for artifact correction in large monitoring networks. The RM assumes a linear relationship between measured OC and PM mass: a constant slope (OC mass fraction) and a constant intercept (RM artifact estimate). These assumptions are not always valid. Additionally, outliers and other individual data points can have a large influence on the RM artifact estimates. The RM yields results within the range of measurement-based methods for some datasets and not for others. Given that the adsorption of organic gases increases with atmospheric concentrations of organics, subtraction of an average artifact from all samples (e.g., across multiple sites) will underestimate OC for lower-concentration samples (e.g., clean sites) and overestimate OC for higher-concentration samples (e.g., polluted sites). For relatively accurate, simple, and cost-effective artifact OC estimation in large networks, the authors suggest backup filter sampling on at least 10% of sampling days at all sites with artifact correction on a sample-by-sample basis as described herein.

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Discrete measurements of reactive gases and fine particle mass and composition during the 1999 Atlanta Supersite Experiment

et al. 2003

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[1] During the Atlanta Supersite Experiment (ASSE) in August 1999, a three-channel particle composition monitor (PCM) was used to measure PM 2.5 mass and composition as well as gas-phase NH 3 , HCl, HNO 3 , HONO, SO 2 , and acetic, formic, and oxalic acids over integrating periods of 10-24 hours. The period was characterized by stagnant periods associated with high temperatures, relative humidities, and UV radiation, underlying parameters causing photochemical activity with intense ozone, and PM 2.5 formation. Analysis of diurnal measurements points to photochemical sources of HNO 3 , HONO, acetic, and formic acids. NO 2 denuder artifact reactions are assessed, and it is found that the secondary heterogeneous O 3 reaction potentially overcorrects the nitrite to nitrate oxidation step on the denuder walls, underestimating [HNO 3 ] and correspondingly overestimating [HONO]. The high ambient humidity caused gravimetric mass to be systematically high by about 20 ± 8%, which was interpreted as hydrate artifact and corrected for. Despite this correction, and inclusion of other organic elements (OOE) (OOE = 0.6 * organic carbon (OC)), an average percent fraction unidentified mass of 13 ± 10% relative to the total reported mass concentration still remained. However, if semivolatile OC collected on an XAD-coated quartz backup filter placed downstream of an XAD-denuded quartz front filter are included, an almost complete closure in the mass balance is achieved. The possible use of different OOE factors for OC and semivolatile OC (here 0.6 and 0.4, respectively) is also investigated, taking into account the different physical properties of carbon species collected from quartz front and XAD-coated quartz backup filters. It can be speculated that photochemically well-aged and well-mixed air masses contain organic compounds with more highly oxygenated and less volatile functional groups, whereas under more stagnant conditions, particle-phase organics might be less oxygenated and therefore more volatile. Sulfate and all organic compounds (including particle bound light organic acids, organic carbon, and OOE) are the main identified contributors to overall PM 2.5 mass with 32 ± 8 and 39 ± 12%, respectively. Acidity calculations based on the particle-phase SO 4 2À /NO 3 À /NH 4 + system show slightly acidic conditions.

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Comparison of Sampling Methods for Semi-Volatile Organic Carbon Associated with PM2.5

Cited by 17 publications

References 21 publications

Comparison and evaluation of in situ and filter carbon measurements at the Fresno Supersite

Comparison and evaluation of in situ and filter carbon measurements at the Fresno Supersite

Correction Methods for Organic Carbon Artifacts When Using Quartz-Fiber Filters in Large Particulate Matter Monitoring Networks: The Regression Method and Other Options

Discrete measurements of reactive gases and fine particle mass and composition during the 1999 Atlanta Supersite Experiment

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