|Title||Quantitative determination of PAHs in biochar a prerequisite to assure its quality and safe application|
|Publication Type||Journal Article|
|Year of Publication||2012|
|Authors||Hilber, Isabel, Blum Franziska, Leifeld Jens, Schmidt Hans-Peter, and Bucheli Thomas D.|
|Journal||J. Agric. Food Chem|
Biochar is increasingly promoted as a beneficial soil conditioner. However, it may contain residues of polycyclic aromatic hydrocarbons (PAH) as a result of its production by pyrolysis. To date, analytical methods to analyze PAHs in biochar quantitatively are hardly available. This study presents an optimized and validated procedure to quantify the 16 US EPA PAHs in biochar. PAHs were best extracted with Soxhlet for 36 hours using 100 % toluene. Average absolute recoveries of isotope labeled internal standards used for each analyte from three different biochars ranged from 42 to 72 %, and relative recoveries were between 71 and 105 %. The limits of detection were biochar-dependent, but on average a factor of >50 lower than quantified PAH concentrations (9 - 355 mg kg<sub>dry weight</sub><sup>-1</sup>). The established method prepares the ground for a harmonized protocol for PAH analysis of biochars, a necessity for biochar quality control, registration, and legislation.