Method development for the determination and quantification of fatty acids using Solid Phase Microextraction (SPME) coupled with gas chromatography

• Main Author: Gineta, Mary Audrey Constantino
• Format: text
• Language: English
• Published: Animo Repository 2005
• Subjects: Fatty acids; Extraction (Chemistry); Gas chromatography; Analytical chemistry > Technique; Chemistry
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/3354; https://animorepository.dlsu.edu.ph/context/etd_masteral/article/10192/viewcontent/CDTG004009_P__1_.pdf
• Institution: De La Salle University

A novel and simple method of determining the fatty acids of bouillons using solid phase microextraction (SPME) coupled with gas chromatography has been developed. The bouillon samples were dissolved in 5mL distilled water and was subjected to solid phase microextraction (SPME) using a 100µm thick poly(dimethylsiloxane) (PDMS) fiber for 15 minutes at 60°C with the solution being stirred. The extracted fatty acids on the SPME fiber were desorbed into the GC-MS for qualitative analysis. Based on the GC- MS profile, out of the four major fatty acids detected, octanoic acid and decanoic acid were chosen to demonstrate capability of SPME-GCFID for quantification. The amounts of octanoic acid and decanoic acid were determined by GC-FID using the external standard calibration curve and standard addition method. Optimized conditions were used in all analyses namely, liquid volume: 5 mL in a 9 mL vial, extraction temperature: 60°C, and fiber depth, 2.1 cm. The extraction time for octanoic acid determination was 17 minutes while that for decanoic acid was 22 minutes. However, when both acids are present, extraction time would depend on the concentration ratio of octanoic to decanoic acid. The external calibration curves (peak area vs concentration of fatty acid) with coefficient of determination , R2 values ranging from 0.9917 to 0.9976, showed significant linear relationship in the concentration range of 1 to 30 ppm. Standard addition method on the other hand also showed good linearity (R2 > 0.9531) depending on the broth sample used. Results showed that shrimp has the highest octanoic acid content (8.71ppm) while chicken has the highest decanoic acid content (21.8 ppm) These amounts are based on the analysis by standard addition method as recommended by SUPELCO (developer/manufacturer of SPME fiber kits) and is preferred in quantitative analysis of samples with complex matrix of fats and humic substances.