Determination of fatty acid in fresh cooking oil and used cooking oil using gas chromatography equipped with flame ionization detector (GC-FID) and gas chromatography equipped with mass spectrometry detector (GS-MSD) / Nur Fatima Mohd Arsad

Fatty acid in fresh and used (a few times) cooking oil used were determined by using gas chromatography flame ionization detector (GC-FID) and gas chromatography mass spectrometry detector (GC-MSD). The injector port and detector temperature for GC-FID analysis was 250 °C with 70.0 mLs- 1 carrier gas flow, while for GC-MSD analysis, the injector port and detector temperature were 200 °C and 300 °C respectively with 1.0 mLmin-1 carrier gas flow. The concentration of fatty acid in different samples were determined for methyl laurate, methyl myristate, methyl palmitate, methyl stearate and methyl linoleate. The concentration were compared between fresh cooking oil and oil that had been used for five times. The cooking oil for FRESH sample has the highest amount of fatty acids which were methyl laurate (71.3 ppm), methyl myristate (1505.7 ppm), methyl palmitate (355973.7 ppm), methyl stearate (63702.7 ppm) and methyl linoleate (12894.6 ppm). The cooking oil for COOK4 sample which had been used for four times has the lowest amount of fatty acids which were methyl laurate (14.5 ppm), methyl myristate (203.3 ppm), methyl palimtate (43635.8 ppm), methyl stearate (7265.1 ppm) and methyl linoleate (2074.6 ppm). Based on this study, as the number of times the oil was used increased, the fatty acid content decreased but at the second time frying, the fatty acid content increased followed by decreasing at fourth time frying.