The fresh cooking oil was mustard oil which was purchased in supermarket. Waste cooking oil were
collected from restaurants in Taiwan and then filtered to remove any inorganic residues and suspended
matters. All the chemicals used in experiments were purchased from Merck chemicals. The certified
reference standards for Gas Chromatography (GC) were purchased from Sigma-Aldrich.
The microwave oven was Panasonic NN-SF550, and also was modified Taiwan. The maximum input
power was 1000W. The Fig 2 was the modified microwave.