Method development for the quantitative determination of short chain fatty acids in microbial samples by solid phase extraction and gas chromatography with flame ionization detection

Abstract

Abstract Background In order to quantitatively measure short chain fatty acids (SCFAs) in microbial samples, sample preparation and analytical conditions using gas chromatography with flame ionization detection (GC-FID) were established. Methods The extraction of SCFAs with ethyl ether-hexane (1:1, v/v) followed by the aminopropyl solid phase extraction (SPE) was carried out. An acid-modified poly(ethylene glycol) GC column was used for the chromatographic separation of four volatile fatty acids. Results Good linearity was obtained with r > 0.999 in the calibration range. The limits of quantification (LOQs) of the analytical method were in the ranges of 5.71 to 11.20 μg/mL. The overall recoveries excluding acetic acid ranged between 96.51 and 108.83% with relative standard deviations (RSD) below 10% for the entire procedure from the results of matrix spiking experiments at three concentration levels. Conclusion The analytical method was validated in accordance with the requirements of the international guideline. The method enables the use of the most commonly used technology without derivatization and the elimination of interferences in the sample matrix.

Keywords

• Short chain fatty acids (SCFAs)
• Microbial samples
• Gas chromatography with flame ionization detection (GC-FID)
• Solid phase extraction (SPE)