Longer adsorption time maybe be necessary due to strong biochar-tar affinity.
What is the goal - measurement of PAH adsorption on biochar, i.e. determining adsorption capacity? In an inert situation (without microbiological transformations)?
I suppose that you plan to detect 16 PAHs in aqueous phase with biochar. It's necessary to seperate the biochar from the solution by centrifugation after adsorption equilibrium. And then the concentration process may be needed before loaded by instrument. I have some experience on detection 16 PAH by HPLC , GC or GC/MS. If you have any other questions, please email me. [email protected]
Perhaps you should think about a clean up in the form of SPE (depending on measuring instrument). And as Fei Liu already said, a concentration of the sample may be needed (you can use 100 - 300 ul inlets for the GC vials).
For further questions please mail me: [email protected]
Thank you very much for the answers. To Mr Sobisch: this is not easy for me to answer, as the biochar in the soil will not be in an inert situation as it will be subject to microbiological transformations - which is the goal of biochar in soil anyway. For comparing with the environmentally set limits though, we have to assume inert situation, and yes, adsorption capacity. SO far we apply the standard also for the biochar samples, I was just wondering if this needs adjustment if we want to develop biochar standards.
Dear Lydia,
for this situation I would strongly suggest that you do the determination after the usual extraction step and in addition after surplus saponification by KOH in MeOH under reflux to get an idea about the so called bound residues.
For reference see work by A. Eschenbach / R. Mahro et.al.
Dear Lydia，
PAHs can be detected based on EPA 8100(GC-FID),8310(HPLC) and 8270(GC-MS).But as I know, extraction-clean up-concentration is very important. If you extract PAHs from siol with biochar, I suggest ASE is better. Soxhlet extraction is almost OK. In any case, biochar must be seperated from extraction phase.
I would necessarily recommend you to follow a cleanup procedure like SPE, silicagel chromatography or a combination of alumina/silica.
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