Head Space Single Drop Micro Extraction Gas Chromatography Flame Ionization Detection (HS-SDME-GC-FID) Method for the Analysis of Common Fatty Acids

Objectives: Post-marketing/surveillance studies show that most of the many vegetable oils that are sold with health-promoting claims or statements with high nutritional values and are beneficial against diseases are off-limits of related monographs/criteria. Defining the oil with a fast, cheap, and efficient analytical method is needed to express fatty acids in any herbal product to authenticate, trace, specify, and classify the content. Materials and Methods: Here, we define a new simple tool with a headspace single drop microextraction (HS-SDME) method coupled with a gas chromatography-flame ionization detector (GC-FID) for the analysis of common fatty acids (FAs) in oils. Linolenic acid, gamma-linolenic acid, and linoleic acid in olive oil, thyme oil, and fish oil were determined. Derivatization was performed with 0.2 mL of 2 mol/L KOH in methanol to transfer the FAs of oils into their methyl esters (FAMEs). Then, FAMEs were extracted using a head space single drop, which is 2.0 mu L of sodium dodecyl sulfate:1butanol (1:3, v/v) mixture. Results: The most suitable extraction condition was that 360 mu L of the FAMEs, 2.0 mL vial, 0.07 g NaCl as a salting-out effect, 45degree celsius extraction temperature, and 35 min extraction time. The precision of the method was below 12%, with accuracy validated by the GC-FID reference method. Conclusion: The HS-SDME can be used effectively for extracting FAs from oils for improved analysis of other FAs. The method is of direct importance and relevance for the herbal, pharmaceutical, and cosmetics industries.