Semi-automated disk-type solid-phase extraction method for polychlorinated dibenzo-p-dioxins and dibenzofurans in aqueous samples and its application to natural water

A disk-type solid-phase extraction (SPE) method was used for the extraction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in natural water and tap water. Since this SPE system comprised airtight glass covers with a decompression pump, it enabled continuous extraction with semi-automation. The disk-type SPE method was validated by comparing its recovery rates of spiked internal standards with those of the liquid–liquid extraction (LLE). The recovery ranges of both methods were similar in terms of 13C-labeled internal standards: 64.3–99.2% for the LLE and 52.4–93.6% for the SPE. For the native spike of 1,3,6,8-tetrachlorinated dibenzo-p-dioxin (TCDD) and octachlorinated dibenzo-p-dioxin (OCDD), the recoveries in the SPE were in the normal range of 77.9–101.1%. However, in the LLE, the recoveries of 1,3,6,8-TCDD decreased significantly. One of the reasons for the low recovery is that the solubility of this congener is high. The semi-automated SPE method was applied to the analysis of different types of water: river water, snow, sea water, raw water for drinking purposes, and tap water. PCDD/F congeners were found in some sea water and snow samples, while their concentrations in the other samples were below the limits of detection (LODs). This SPE system is appropriate for the routine analysis of water samples below 50 L.