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 μg 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%).