PTAG
Shimadzu LC20AT HPLC (Kyoto, Japan) was used to determine PTAG in oxidized oil following the previously reported method (Hwang, et al., 2014). Oil sample dissolved in dichloromethane (about 10 mg oil in 10 ml dichloromethane) was transferred to an autosampler vial, and the solution (10 µl) was injected into a size exclusion column (PLGel, 5 μm, 300 x 7.5 mm, 100Å pore size, Polymer Labs, Amherst, MA, USA). A Sedex model 75 evaporative light scattering detector (ELSD) (Sedere, Inc., Cranbury, NJ, USA) was used as detector. The operation temperature of ELSD was 40 ºC, and nebulizer gas was nitrogen (3.5 bar). Percentages of peaks in chromatograms are reported.