Chemical characterization of carbonaceous aerosol in Monterrey (Mexico) Chemical characterization of carbonaceous aerosol in Monterrey (Mexico) Statement of Work: Chemical characterization of carbonaceous aerosol in Monterrey (Mexico) Pierre Herckes and Matthew P. Fraser, Arizona State University The objective of this research project is to analyze samples of organic particulate matter (PM) collected in Monterrey, Mexico, to aide in the interpretation of the relative contribution of different sources to ambient PM levels. This will be accomplished by quantifying total carbonaceous particle levels and the distribution between organic and elemental carbon using a thermal-optical method and extraction, derivatization and quantification of unique molecular markers by gas-chromatography- mass spectrometry (GC-MS). Samples will be collected by the team of Professor Mendoza at the Instituto Tecnolgico y de Estudios Superiores de Monterrey and provided to AUS for analysis. All chemical analysis will be performed at ASU, in part by ASU personnel in part by a visiting scientist from ITESM. Task 1: Analysis of Total, Elemental and Organic Carbon in Samples Samples, ambient samples and field blanks from 3 field studies as well as 1 source characterization study, will be analyzed using a thermal-optical technique that separates organic and elemental carbon based on volatility and combustibility while simultaneously monitoring pyrollysis. This thermo-optical technique releases organic material in an inert atmosphere via volatilization, oxidation to CO2, subsequent reduction to form methane, and quantification by flame ionization detection. Subsequently, in an oxygen containing atmosphere at an elevated temperature, elemental carbon is released through combustion and quantified as CO2. During this process of separating elemental and organic carbon, pyrollysis of organic material to elemental carbon is monitored by absorption of visible radiation in the ambient aerosol sample, and a pyrollysis correction will be performed. Replicate analysis will be conducted on 10% of samples for precision determination and the instrument will be calibrated with an authentic methane standard after each sample run. Data will be reduced to determine corresponding ambient concentrations of elemental, organic and total carbon based on sample information and blank correction and supplied to Prof. Mendoza. Task 2: GC-MS Speciation of Samples A recovery standard will be added to each sample prior to extraction to monitor the extraction efficiency and loss on concentration of marker species. This recovery standard will include isotopically labeled compounds of varying polarity and volatility to span the range of species to be used as markers. Analysis will include extraction of organic tracers with a dichloromethane according to established procedures. Final sample extracts will be derivatized using diazomethane and [bis(trimethylsilyl)trifluoroacetamide] to convert convert polar compounds to non-polar derivatives which can be more accurately quantified by GC-MS.
|Effective start/end date||9/1/12 → 8/31/14|
- OTHER: Foreign University: $25,999.00
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