Determination of Fatty Acids in Zanthoxyli Semen Based on Solidification of Floating Organic Drop Liquid Phase Microextraction with Gas Chromatography

Abstract

The objective of this research was to develop a solidification of floating organic drop liquid phase microextraction coupled with gas chromatography (GC) and apply it to simultaneous enrichment and determination of five fatty acids, including palmitic acid, stearic acid, oleic acid, linoleic acid and α-linolenic acid, in Zanthoxyli Semen. Several parameters influencing the extraction efficiency or enrichment factor, such as the volume of the extraction solvent (n-dodecanol), extraction time, stirring rate, salt concentration and sample phase volume, were carefully selected. Under the optimum conditions, linearities were 5.09–120.48 μg mL⁻¹ for palmitic acid (r = 0.9984), 10.13–120.00 μg mL⁻¹ for stearic acid (r = 0.9993), 4.18–99.12 μg mL⁻¹ for oleic acid (r = 0.9990), 1.32–132.00 μg mL⁻¹ for linoleic acid (r = 0.9990) and 1.62–161.72 μg mL⁻¹ for α-linolenic acid (r = 0.9991), respectively. Detection limits were in the range of 0.12–0.16 μg mL⁻¹. Satisfactory precision (2.6–9.6%) and accuracy (90.2–109.1%) were also achieved. Compared with traditional liquid–liquid extraction with GC, the determination results of α-linolenic acid, one of the active ingredients in Zanthoxyli Semen, had no significant difference (95% confidence level) in accuracy and precision, and the proposed procedure exhibited low solvent consumption, simple steps, a short extraction time and low LOD.