AOAC 2018 Methods

by applying an empirically determined representative transformation factor with every analytical batch. This approach also compensates for any unavoidable variations in time and temperature during the transesterification. External calibration as well as consideration of absolute recoveries of the analytes might be applied, but are not necessary for routine analysis as intra- and interlaboratory studies have demonstrated the effectiveness and accuracy of single-point calibration. All analyte results are reported per gram of sample as purchased or prepared and not on the basis of extracted fat. B Apparatus and Materials Some consumables, such as glassware, filters, and certain plastic materials, may contain free MCPD, causing background contamination. In the case of contaminated consumables, bake-out glassware and/or replace/rinse non-thermo-resistant materials. Screw caps for vials should be Teflon-sealed. Glassware used for HUPsSE should be mechanically robust with inert and tight sealings. a. 12 mL screw cap vials (WIC41510) and screw caps with Teflon seals (WIC43931) used for HUPsSE: e.g., Wicom Germany GmbH (Heppenheim, Germany). If other HUPsSE extraction vessels are used, take caution to ensure appropriate suitability. There is the risk of losing samples if seals are not tight or if glassware bursts (the latter is not a specific safety risk as the surrounding water prevents acceleration of glass fragments). b. Plastic rack suitable for holding 12 mL crew cap vials: e.g., 211-0220 / 211-0222, VWR International GmbH (Darmstadt, Germany). c. Bulbs for Pasteur pipettes, 2 mL internal volume: e.g., VWR International GmbH (Darmstadt, Germany). d. Solvent evaporation devices, pressure-regulated nitrogen dispenser with replaceable outlets (Pasteur pipettes), and temperature-regulated heating plate e. Ultrasonic bath, programmable temperature and time: e.g., USC-THD/HF, VWR International GmbH (Darmstadt, Germany). f. Disperser: e.g., Ultra Turrax T25 with S25N-8g disperser tool (8 mm outer diameter of stator), Janke & Kunkel GmbH & Co KG (Staufen, Germany). g. Gas chromatograph equipped with programmable temperature vaporizor (PTV) injection system: e.g., 7890A Agilent Technologies (Santa Clara, California, USA). h. GC conditions: Injection volume: 1 µL to 2 µL; Carrier gas: Helium 4.0 or better; constant carrier gas flow: 1 mL/min to 1.5 mL/min; PTV temperature program: e.g., 85°C, with 300°C/min to 165°C, 10 min isothermal, with 300°C/min to 320°C, 8 min isothermal; Injector: e.g., splitless, purge flow 50 mL/min at 0.5 min to 1 min, septum purge 3 mL/min; GC oven temperature program: e.g., 85°C, isothermal 0.5 min, with 6°C/min to 150°C, with 12°C/min to180°C, with 25°C to 280°C, isothermal 8 min; Column: e.g., stationary phase 50% diphenyl, 50% dimethylpolysiloxane, 30 m, 0.25 mm ID, 0.25 mm film thickness. i. Single quadrupole mass spectrometer: e.g., 5975–5977 series, inert ion source: Agilent Technologies (Santa Clara, California, USA). j. MS conditions: Electron-impact (EI), selected ion monitoring (SIM), low mass resolution k. Detected ion traces related to the mass to charge ratios (m/z) from the phenylboronic derivatives of the analytes:

1. 3-MCPD-d 5 : m/z = 149/150/201/203 2. 3-MCPD: m/z = 146/147/196/198