Determination of pentachlorophenol and its oil solvent in wood pole samples by SFE and GC with postcolumn flow splitting for simultaneous detection of the species

An alternative approach is described for the measurement of pentachlorophenol (PCP) and its oil solvent in wood samples by supercritical fluid extraction (SFE) and gas chromatography (GC). The determination is achieved over a single chromatographic run using postcolumn now splitting for simultaneous ECD/FID detection of the SFE extracted species. First, PCP and oil components sure quantitatively extracted from a 0.3-g wood sample using 10% MeOH/CO2 supercritical fluid at 0.65 g/mL and 120 degrees C. An aliquot of the SFE solution is then mixed with 10 mt of a buffered aqueous phase at pH 9.4. After PCP is acetylated by the addition of 500 mu L of acetic anhydride, it is followed by its extraction with 2.00 mt of hexane along with oil. Then, 0.5 mu L of supernatant organic phase is injected into the GC for a selective and simultaneous determination of the species. The method has a linear response over 3 orders of magnitude for both species with a linear regression correlation coefficient higher than 0.98 (95% confidence limit) and an absolute detection limit of 60 ng of PCP and 80 mu g of oil per 0.1-g wood sample. The precision (relative standard deviation) is 4% for PCP and 1% for oil as established for a typical average concentration sample. The accuracy of the SFE GC-ECD/FID combined technique for PCP and oil was assessed by analyzing wood samples collected from newly and inservice PCP/oil-impregnated red pine poles.