Fig. 4From: Method development for the quantitative determination of short chain fatty acids in microbial samples by solid phase extraction and gas chromatography with flame ionization detectionOverlay chromatograms of the microbial medium sample spiked with SCFAs (50 μg/mL) prior to (A) and after (B) adopting SPE cleanup. Peak identities were as follows: (1) acetic acid, (2) propionic acid, (3) pivalic acid (IS), (4) butyric acid, (5) valeric acidBack to article page