Methodology for Polycyclic Aromatic Hydrocarbons Extraction from Either Fresh or Dry Spent Mushroom Compost and Quantification by High-Performance Liquid Chromatography–Photodiode Array Detection

Abstract

Polycyclic aromatic hydrocarbons (PAH) are a family of compounds classified as persistent organic pollutants, which are hazardous for environmental and human health. White rot fungi are organisms that are able to remediate PAH from polluted soils. Spent mushroom compost (SMC) is employed for soil bioremediation and environmental research. In this study, four solvents [acetone/dichloromethane (CH2Cl2) 1:1 mixture; acetone/hexane 1:1 mixture; methanol, and acetone], which are among those already used for PAH solvents, were chosen to be combined with two extraction procedures (ultrasound and orbital shaking). All extracted PAH were quantified by high-performance liquid chromatography (HPLC)–photodiode array detection (PDA). Certified soil CRM141, containing 16 PAH included in the U.S. Environmental Protection Agency priority list, was used for methodology validation. The orbital shaking procedure was selected because all detected and quantified PAH were within the CRM141 prediction interval, and there was less variability for all checked solvents than in the ultrasonic procedure. Once the orbital shaking methodology was selected, fluorene, phenanthrene, anthracene, and pyrene standards were added to fresh (60% moisture content) and dry SMC. The orbital shaking procedure was carried out over 24 h to avoid PAH degradation, and 1 month later to provide PAH interaction with solid matrix in this period of time. The PAH orbital shaking extraction over dry SMC showed large recovery percentages for all tested solvents. The PAH extracted from fresh SMC showed biodegradation after 24 h. Acetone/CH2Cl2 (1:1), methanol, and acetone solvents employed over fresh SMC recovered less than solvents over dry SMC. Acetone/hexane (1:1) recovered more than 80% and did not show any decrease in recovery over fresh SMC. Results indicate that it is not necessary to include a drying step prior to PAH extraction if the acetone/hexane (1:1) solvent mixture is employed. The recommended methodology for PAH extraction includes orbital shaking of fresh compost with acetone/hexane (1:1) solvent mixture and quantification by HPLC-PDA.