Material and Methods
Supelco 37 Component FAME Mix, Canola oil analytical standard, boron trifluoride (14% in methanol) and sodium methoxide (0.5M in methanol) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Triheneicosanoin and individual FAME used for identification purposes were purchased from Nu-Chek Prep (Elysian, MN, USA). BCR 632A (anhydrous butter) was purchased from the EU Joint Research Centre (Geel, Belgium). Partially hydrogenated oils and other food oils were collected during previous studies. Samples were converted to FAME at the concentration of 20 mg/mL applying AOCS Official Method Ce 2-66 [9] after the addition of triheneicosanoin as internal standard (5% w/w).
Gas chromatographic analyses were performed with an Agilent 8890 GC equipped with a split/splitless injection port, FID detector, and Supelco SP2560 capillary column (0.25 mm x 100 m, 0.20 µm thickness, Supelco, Bellefonte, PA, USA). Hydrogen was the carrier at 1 mL/min constant flow and 1 µL of sample was injected with 100:1 split ratio. Temperature program method 1: 60°C for 5 min, ramp 15°C/min to 165°C, hold 1 min, ramp 2°C/min to 184°C, hold 25 min, ramp 4°C/min to 225°C, hold 20 min. Temperature program method 2: 60°C for 5 min, ramp 15°C/min to 165°C, hold 1 min, ramp 2°C/min to 190°C, hold 8 min., ramp 4°C/min to 175°C, hold 11 min, ramp 4°C/min to 225°C, hold 20 min.