You referenced ASTM D4600, which is an occupational exposure method for benzene. Exactly what are you asking? Are you trying to determine benzene via solvent extraction of TPM and PM2.5 samples or are you trying to estimate how benzene will partition given known concentrations of benzene, TPM and PM2.5 in the ambient environment? If you are trying to extract benzene from a PM sample train, the sampling protocol and dealing with both negative and positive SVOC artifacts becomes important. I would point you towards the body of work published by Glenn Cass, James Schauer and others and their use of denuder-filter-XAD samplers. Estimating ambient partitioning from benzine and PM data is a lot trickier since partitioning of SVOC's into gas phase vs. particle phase involves complex processes such as heterogenous/homogenous nucleation, adsorption and absorption interactions with ambient aerosols, etc., along with dependencies on temperature, ambient aerosol concentrations, ambient aerosol size distribution and surface area, concentrations of other semi-volatile compounds, oxidation reactions that transform gas-phase and semi-volatile compounds and so on.
Dear Joseph I want to to do gravimetric estimation of the organic matter, present in the air borne particulate matter ; which are soluble in the benzene.
Hope it will more clear to you now and you will be advise me better ..
thank you
My memory seems to be selective. While I remembered Cass and Schauer doing work in this area, the use of coated denuders to prevent gas-phase positive artifact from being counted along with particle-phase SVOC (benzene included) and interfering with proper gas/particle partitioning of the sample was chiefly developed by Lara Gundel at Lawrence Berkely National Laboratory in the late 1990's to early 2000's (e.g., Swartz, Stockburger and Gundel, ES&T 2003, 37, 597-605). I have used similar sampling trains for source measurement although I realize you are conducting ambient measurements. For source measurements, we tended to use XAD-2 instead of XAD-4 (Gundel) as the polymer adsorbent for coating the denuders and we also added a chilled XAD-2 sorbent-bed downstream of the filter pack to quantify negative artifact (i.e., SVOC loss from the filter pack). I believe that glass annular denuders are available from URG (urgcorp.com). I have also seen them custom-made. If you are making them yourself, surface roughness of the glass is important to getting good adherence of the XAD material to the denuder surfaces.
Also, if you wind up sampling SVOC's using polymer sorbents in this manner, I would recommend spiking with isotopically labelled internal standards to check for sample recovery at diffeent stages of the process (initial air sampling, extraction, sample concentration, etc.)