This method measures the percentage of various fatty acids in the food as a percentage of total fatty acids. The sample processing is simple and fast; the method is accurate and the sensitivity is high.

1.Principle

Gas chromatography uses a column to charge a support and fixative solution, and carries the mixture to be analyzed into the column with a carrier gas. Under certain conditions of temperature and pressure, the gas components are in the gas of the carrier gas and the fixative film. The partition coefficient in the liquid two-phase phase is different. As the carrier gas flows forward, the components of the sample are repeatedly distributed in the gas and liquid phases, so that the moving speed of each component of the fatty acid is fast and slow, so that The components are separated. Then separate measurements were made.

2. Operation steps

Weigh 30--100mg (about 2-6 drops) of oil, put it into a 10ml volumetric flask, add 1-2ml of 30~60 °C boiling range petroleum ether and benzene mixed solvent (1:1), gently shake to dissolve the oil . Add 1-2 ml of 0.4 mol/L potassium hydroxide-methanol solution and mix. After standing at room temperature for 5 to 10 minutes, distilled water was added to raise all the petroleum ether benzyl ester solution to the upper part of the neck of the bottle, and it was set to be clarified. When the supernatant is turbid and urgent to be analyzed, a few drops of absolute ethanol can be added dropwise and clarified within 1-2 minutes. The supernatant was aspirated, and nitrogen was blown at room temperature to concentrate, and the obtained concentrate was used for gas layer analysis.

3. Precautions

The difference between the two measurements of the same sample shall not exceed 5% of the average of the two measurements.