Development of method and analysis protocol for fatty acids derivatives of castor oil by using gas chromatography-mass spectrometry

Castor oil is a vegetable oil extracted from castor beans, known for its diverse applications across the chemical industry, food industry, skincare products, biodiesel components, and pharmaceuticals. Analyzing the fatty acid composition of castor oil using Gas Chromatography-Mass Spectrometry (GC-MS) can be complex due to various factors inherent to fatty acids and the oil's composition. Therefore, the goal of this study is to effectively separate and analyze the major fatty acids present in castor oil using GC-MS. Castor oil was methylated using alcoholic potassium hydroxide, then neutralized with salicylic acid and centrifuged. The supernatant was diluted and injected into the GC-MS with a developed temperature program. The results indicated that castor oil contains five fatty acids: ricinoleic acid methyl ester, oleic acid methyl ester, linoleic acid methyl ester, stearic acid methyl ester, and palmitic acid methyl ester, with respective concentrations of 87.63%, 1.81%, 6.57%, 2.93%, and 1.07%. Among these, methyl ricinoleate was the most abundant at approximately 87.36%, while palmitic acid methyl ester had the lowest concentration at 1.07%. The order of fatty acids detected was methyl ricinoleate > linoleic acid > stearic acid > oleic acid methyl ester > palmitic acid. To our knowledge, this is the first report of an easy and efficient method for the analysis of castor oil. In conclusion, the developed methylation of castor oil and gas chromatography temperature program are suitable for the routine analysis of castor oil.