Analysis of alkylphenols and bisphenols in soils using liquid chromatography-tandem mass spectrometry

Methods useful for the extraction of alkylphenols from soil samples were assessed. A comparison is made of the four extraction techniques that are most commonly used to extract phenolic compounds from soil, such as bisphenol A, bisphenol F and alkylphenols (4-t-OP, iso-NP, 4-OP and 4-n-NP). Soxhlet extraction, ultrasonic-assisted extraction (USE), accelerated solvent extraction (ASE) and the so-called Quick, Easy, Cheap, Effective, Rugged and Safe extraction (QuEChERS) were included. Modifications of the QuEChERS technique such as original, citrate and acetate were investigated. The effects of basic purification sorbents used for QuEChERS extracts such as a primary and secondary amine (PSA), C18 endcapped sorbents and graphitised carbon black (GCB) were tested. A derivatisation step prior to the final analyses by liquid chromatography coupled to a triple quadrupole analyser operating in tandem mass spectrometry (LC-MS/MS) was performed by using dansyl chloride (DNSC). The best extraction of the monitored compounds from spiked soil was obtained using QuEChERS extraction. Recoveries of phenolic compounds using the QuEChERS technique were in the range from 67% to 114%. The lowest extraction recoveries (16-73%) were obtained using ultrasonic extraction. The QuEChERS method was successfully applied for the analysis of alkylphenols in soil samples. Instrumental limits of quantification and limits of detection ranged from 0.08 to 0.83 pg per injection and 0.02 to 0.25 pg per injection, respectively.