AOAC 2018 Methods

(d) Dilution procedure (Oils) 1. Weigh 0.50 ± 0.01 g or 0.5 mL of a thoroughly homogenized sample into a 25-mL volumetric flask. 2. Add approximately 20 mL of EtOH and briefly hand-shake until the sample is dissolved. Dilute the flask to volume with EtOH. Note: Sonication may be used to support dissolution of the sample. 3. Filter 3-mL aliquot of the extract using plastic syringe fitted with a 0.22 µm PFTE syringe filter into a 15-mL centrifuge tube. 4. Perform 10-fold and 100-fold dilution of the extract with MeOH in 10-mL volumetric flasks. Note: Higher dilution factors can be employed if required. 5. Transfer aliquots of the original extract and diluted extracts into 2-mL amber LC vials, cap and briefly vortex to mix. 6. Analyze by LC-DAD(MS). G. Determination (a) LC Operating Conditions. 1. Column: Supelco Ascentis Express C18, 2.0 µm, 150 x 2.1 mm 2. Column temperature 25°C 3. Mobile phase A: 20 mM aqueous NH 4 HCO 2 , pH 3.2 4. Mobile phase B: ACN 5. Elution gradient see Table 2018.11B 6. Injection volume: 3 µL 7. Autosampler temp.: 10°C 8. Run time: 17 min Note: Example chromatograms of calibration standard solution are provided in Figure 2018.11 . Table 2018.11B . Gradient elution program Time (min) A (%) B (%) Flow (mL/min) 0.00 40 60 0.400 12.00 5 95 0.400 12.01 5 95 0.600 14.00 5 95 0.600 14.01 40 60 0.400 16.00 40 60 0.400