Edf 8999

Native dioxin/furan mixtures (M-8280A-PAK/M-8280B-PAK, containing 10 PCDD/F congeners), native NDL-PCB mixtures (PCB-DUTCH7-SET), and native DL-PCB (12 individual standard solutions), which were used for the fortification of soybean oil, were purchased from AccuStandard (New Haven, CT, USA). ¹³C₁₂-labeled PCDD/F compounds, which were used as surrogates (EDF-8999) and internal standards (EDF-5999) for PCDD/Fs, were purchased from Cambridge Isotope Laboratories (Tewksbury, MA, USA). ¹³C₁₂-labeled PCB compounds, which were used as surrogates (WP-LCS and EC-9605 SS) and internal standards (EC-9605 RS) for PCBs, were obtained from Wellington Laboratories (Guelph, ON, Canada). Pre-mixed PCDD/F and PCB calibration standards were purchased from Cambridge Isotope Laboratories and Wellington Laboratories, respectively.
All solvents were pesticide grade and purchased from Duksan Pure Chemicals (Ansan, Kyungkido, South Korea). Aluminum oxide (neutral, 70–200 mesh) and florisil (60–100 mesh) were purchased from Sigma-Aldrich (Shanghai, China). Silica gel 60 (70–230 mesh) was purchased from Merck (Shanghai, China).

PCDD/Fs standards, including an internal standard spike solution (code: EDF-5999); a cleanup standard (code: EDF-6999); a labeled compound stock solution (EDF-8999); a precision and recovery standard solution (EDF-7999); and a calibration solutions (EDF-9999) were purchased from Cambridge Isotope Laboratories, USA. These standards were used to cause spikes in samples and create calibration curves. Solvents such as toluene, hexane, acetone, and nonane (purity > 99.9%), ordered from Merck, New Jersey, USA, were used to wash all tools, bottles, extracts, and clean up methods. The cleanup process involved the use of a multi-layer silica gel dioxin column (28397-U) and a dual-layer carbon reversible tube (28399-U) from Sigma-Aldrich, Steinheim, Germany. Nitrogen (purity > 99,999) from Messer Viet Nam was used for drying in this process.