Determination of tribromophenol and pentachlorophenol and its metabolite pentachloroanisole in Asparagus officinalis by gas chromatography mass spectrometry

A GC-MS method was developed and optimized for simultaneous determination of pentachlorophenol (PCP), 2,4,6-tribromophenol (TBP), and pentachloroanisole (PCA) residues in the edible part of Asparagus officinalis. For this purpose, two procedures were evaluated: the direct separation of PCP, TBP, and PCA and the separation of acetyl-PCP, acetyl-TBP, and non-acetylated PCA. Better sensitivity and quantitative results, especially for PCP, were obtained after acetylation. The residues of PCP and TBP were extracted as phenolates and acetylated in a carbonate solution. Acetylated compounds were extracted by liquid-liquid extraction with hexane, while PCA was directly leached with this solvent. The proposed method allows the rapid quantification of traces of PCP, TBP, and PCA in a concentration ranging between 1.0 and 8.0 ng mL(-1) in solution (corresponding to 0.3 and 8.0 mug kg(-1) in asparagus). In this concentration range, typical recoveries for PCA, TBP, and PCP from asparagus samples were 59%, 86%, and 97% respectively (RSDs 3-7%).