Impact/Purpose:

The goals of this research are to develop a method for measuring Hg concurrently with multiple metals at concentration levels of interest in human and dietary exposure studies using DIN-ICP/MS, and to validate the method by determining the concentration of multiple-metals plus total Hg in (1) drinking water, (2) beverages and (3) archived NHEXAS composite diet samples. A sub-objective of this work is to write a report for research planners that compares the costs and relative merits of the currently available Hg methods. This report would contain single lab data for Hg in dietary samples using ICP/MS, cold vapor atomic absorption (CVAA), and cold vapor atomic fluorescence (CVAF).

Description:

Mercury (Hg) is a Persistent Bioaccumulative Toxin. Currently, low-level mercury (Hg) and low-level multiple-metals analyses require separate methods. Due to the high costs of performing both types of analyses, research planners often have to choose one or the other. For example, during the U.S. EPA's National Human Exposure Assessment Survey (NHEXAS) planners chose to fund multi-metals data collection due to cost restrictions even though Hg data was also desired. At this time, there are archived NHEXAS samples that have never been analyzed for Hg. Without the benefit of a low-level multiple metals method that includes Hg, future research planners will have to make similar cost/benefit decisions. Therefore, it would be advantageous to have one method for digestion and analysis of Hg and multiple metals. Inductively coupled plasma - mass spectrometry (ICP-MS) is an inherently sensitive technique for Hg analyses but sample introduction into the plasma using conventional nebulizers, such as the pneumatic nebulizer or the ultrasonic nebulizer, result in high memory effects causing detection limits to be high. The direct injection nebulizer (DIN) is a sample introduction technique, requiring very low sample volumes, that overcomes these detection limit problems. By using DIN-ICP/MS, it will be possible to perform low-level Hg analysis concurrently with trace metals analyses.

Under this task, microwave acid digestion methods will be developed for a variety of food types, beverages and composite food samples to extract and retain in an acid matrix metals of interest, plus total Hg. The DIN-ICP/MS will then be evaluated for the determination of metals with respect to recovery, detection limits and accuracy. The final product will be a single method for the analysis of metals plus Hg using DIN-ICP/MS to be recommended for use in future human exposure studies by the NERL. This will enable the client to make cost-effective research plans for collecting data on the exposures of the general population to trace metals and Hg from dietary sources. An additional document that compares the currently available Hg techniques will be prepared and delivered to research planners in the NERL to aid them in making decisions in light of the strengths and limitations of current Hg methods.

Record Details:

Record Type:PROJECT

Start Date:10/01/2000

Completion Date:09/01/2002

Record ID: 56072

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Project Information:

Progress :The following outputs, accomplished through an Internal Grant Research proposal ending in 2000, have been valuable in acquiring expertise necessary for this proposed task:

Papers/Proceedings
-- Wu C.Y, E. Arar and P. Biswas, ""Mercury Capture by Aerosol Transformation in Combustion Environments," Paper 96-MP2.02, Air, Water and Waste Management Association meeting, Nashville, Tennessee, June 1996.
-- Wu C.Y, E. Arar, P. Biswas and G. Tyree, "Capture of Mercury in Combustion Environments by In Situ Generated Titania Particles with UV Radiation", Proc. 1996 Fall Meeting of the Eastern States Section of the Combustion Institute, pp. 479-482, Hilton Head, December, 1996.
-- Wu C.Y., T.G. Lee, E. Arar and P. Biswas, "Novel, In Situ Generated Sorbent Methodology and UV Irradiation for Capture of Mercury in Combustion Environments", Proc. EPRI-DOE-EPA Combined Utility Air Pollutant Control Symposium, Particulates and Air Toxics, Washington, DC, August 25-29, 1997.
-- Wu C.Y., T.G. Lee, G. Tyree, E. Arar and P. Biswas: "Capture of Hg in Combustion Systems by In Situ Generated Titania Particles with UV Irradiation", Environ. Engr. Sci. vol.15 (2) pp.137-148, 1998.
-- Hayashi T., T.G. Lee, M. Hazelwood, E. Arar and P. Biswas, "Characterization of Activated Carbon Fiber Filters for Pressure Drop, Submicrometer Particulate Collection and Mercury Capture" final revision submitted to Journal of Air and Waste Management Association, October 1999.
-- Hedrick, E.J., H. Minges, T.G. Lee and P. Biswas, "Development of Impinger Solutions for the Efficient Capture of Gaseous Hg Species Using Direct Injection Nebulization Inductively Coupled Plasma Mass Spectrometry (DIN-ICP/MS) Analysis," proceedings of the 93rd Annual Meeting of the AWMA, Salt Lake City, Utah, June 18-22, 2000.
-- Lee, T.G., E. Hedrick, and P. Biswas, "Comparison of Mercury Capture Efficiencies of Three Different In Situ Generated Sorbents, AIChE Journal, vol. 47, no. 4, April 2001, pp 954-961.
-- Hedrick, E.J., T.G. Lee, P. Biswas, and Ye Zhuang ,"The Development of Iodine Based Impinger Solutions for the Efficient Capture of Elemental Hg Using Direct Injection Nebulization Inductively Coupled Plasma Mass Spectrometry (DIN-ICP/MS) Analysis," Env. Sci. and Tech., 2001, vol 35, pp 3764-3773.
--Hedrick, E.J., P. Biswas, T.G. Lee and Y Zhuang, "The Determination of Mercury Species in Coal Combustion Emissions Using Iodine Based Impingers and DIN-ICP/MS," proceedings of the 94th Annual Meeting of the AWMA, Orlando, FL, June 24-28, 2001.

-- Lee, T.G., E. Hedrick, and P. Biswas, "Kinetics of High Temperature Mercury reaction in the Presence of HCl: Homogeneous Gas and Heterogeneous Gas-Solid Phase," in preparation, 2001.

-- Lee, T.G., E. Hedrick, and P. Biswas, "Kinetics of Heterogeneous Mercury Reaction with TiO2 Sorbent Particles: In Situ Capture Methodologies," Chemosphere, in-review, 2001.

Presentations/Posters

-- Wu C.Y, E. Arar and P. Biswas, "Mercury Control in the Combustion Environment", Poster, The Role of Metallic Species in the Chemistry of Pollutant Formation and Conversion, Cincinnati, OH, April 26, 1996.

-- Wu C.Y, E. Arar and P. Biswas, "Mercury Capture in Combustion Environments by Aerosol Transformation", Presentation at the Spring Meeting of the Central States Section, The Combustion Institute, St Louis, MO, May 5-7, 1996.

-- Wu C.Y, E. Arar and P. Biswas, "Experimental Study of Mercury Control in Combustion by Aerosol Transformation", Presentation at the 15th AAAR Annual Meeting, Orlando, FL, October 14-18, 1996.

-- Biswas, P., C.Y. Wu, T.G. Lee and E Arar, "In Situ Control of Mercury Emissions from Combustors by Aerosol Transformation Using Novel Sorbent Precursors", 5th International Congress on Toxic Combustion By-products, Dayton, OH, June 25-27, 1997.

-- Arar, E., "Application of DIN-ICP/MS for Mercury Analysis", Presentation at Trace Metals Workshop, U.S.

Relevance :The EPA has identified mercury (Hg) as a Persistent, Bioaccumulative Toxic Pollutant (PBT). Dietary exposure is the primary route of exposure to Hg in non-occupational settings. Sub-populations such as children and those who are frequent consumers of fish are at highest risk. It is known that the primary route of exposure to methyl mercury is from fish consumption. Other dietary exposure comes from poultry, dairy and beef. This is often due to the fact that commercial cows and chickens are fed fish meal. The impact of this research will be to make it possible to concurrently perform low-level Hg determinations, along with other trace metals determinations in dietary samples such as drinking water, beverages, and solid foods, in support of NERL human exposure studies.

The primary client for this work is the Human Exposure Analysis Branch of the Human Exposure and Atmospheric Sciences Division of the NERL. Initial consultation with the lead for dietary exposure in the National Human Exposure Assessment Survey led to the development of this task. Periodic progress updates will be conveyed by email and phone to the interested parties in FY02. Their input will be solicited by phone and email as progress is made. The desired outcome is to develop a method and guidance document that will enable the client to make cost-effective research plans for collecting data on the exposures of the general population to trace metals and Hg from dietary sources. A potential client, the Food and Drug Administration, will be contacted and solicited for potential collaboration.

Clients :NERL, ORD

Project IDs:

ID Code :10909

Project type :OMIS