Optimization of ultrasonic-assisted extraction for determination of polycyclic aromatic hydrocarbons in biochar-based fertilizer by gas chromatography–mass spectrometry

Abstract

Application of biochar-based fertilizers is increasingly being considered for its potential agronomic and environmental benefits. However, biochar may contain residues of polycyclic aromatic hydrocarbons (PAHs) as a result of its production by pyrolysis. The strong adsorption of PAHs to biochar makes extraction and analysis of biochar-based fertilizers difficult. This study optimizes the extraction of PAHs in biochar-based fertilizer samples by using an ultrasonic bath for quantification by gas chromatography-mass spectrometry. Among 12 solvents, acetone-cyclohexane (1:1) mixture was selected as the optimum solvent for extraction. Three variables affecting the extraction were studied by Box-Behnken design. The optimum conditions were 57 °C extraction temperature, 81 min extraction time, and two extraction cycles, which were validated by assessing the linearity of analysis, LOD, LOQ, recovery, and levels of PAHs in real biochar-based fertilizer samples. Results revealed that the 16 U.S. EPA PAHs had good linearity, with squared correlation coefficients greater than 0.99. LODs were low, ranging from 2.2 ng g(-1) (acenaphthene) to 23.55 ng g(-1) (indeno[1,2,3-cd]perylene), and LOQs varied from 7.51 ng g(-1) to 78.49 ng g(-1). The recoveries of 16 individual PAHs from the three biochar-based fertilizer samples were 81.8-109.4 %. Graphical Abstract Use of RSM to optimize UAE for extraction of the PAHs in biochar-based fertilizer.

Biochar applications and modern techniques for characterization

“…In this review, two feedstocks have been considered, (1) wheat straw biochar produced at slow pyrolysis (2) and soil amended PAHs biochar produced by combining homogenized biochar with a biological compound fertilizer at a 50 % (w/w) ratio to develop a non-toxic/non-hazardous solvent mixture (1:1 acetone:cyclohexane) instead of toxic/hazardous solvents (e.g., dichloromethane, toluene), for GS-MS analysis as shown in Table 3. This study delivered a novel and proficient method for extraction of PAHs from slow pyrolysis produced biochar and char-based fertilizers (Chen et al 2015). Furthermore, this technique provides acceptable PAHs recovery when introduced to a wide range of biochar samples attained at different pyrolysis conditions, using different biomass materials, signifying, this analytical practice could be used effectively on different biochars.…”

Optimization of a simple, effective, and greener methodology for polycyclic aromatic hydrocarbon extraction from human adipose tissue

“…To the authors' knowledge, UAE probe-type extraction has not yet been applied to the extraction of PAHs as the ultrasound bath type has. [22][23][24][25] However, the UAE probe-type has been used for the extraction of bioactive compounds, 8,26 allowing the successful recovery of analytes without compromising the quality of the extract.…”

Tracking 14C-Labeled Organic Micropollutants to Differentiate between Adsorption and Degradation in GAC and Biofilm Processes

“…For instance, estimating the removal of parent compounds through influent–effluent measurements cannot itself explain biological degradation, 13 and the detection of biological transformation products may be prevented by their potential adsorption onto the activated carbon. While extraction of previously adsorbed micropollutants has been demonstrated, , estimating biological contribution based on transformation product extraction still requires extensive knowledge on potential degradation pathways. Furthermore, the inhibition methods used to compare biologically active and sterilized GAC filters , may not, selectively or completely, inhibit biological processes, and observed differences are still difficult to link directly to biological degradation of micropollutants, due to potential changes in activated carbon adsorption capacity induced by degradation of competing natural organic matter.…”