Headspace solid-phase microextraction with 1-pyrenyldiazomethane in-fibre derivatisation for analysis of faecal short-chain fatty acids.

Short chain fatty acids (SFCAs) are nutritionally important products of colonic bacteria. Their analysis in faeces is problematic. We report a headspace solid-phase microextraction procedure in which faecal SCFAs are derivatised on the fibre in-situ with 1-pyrenyldiazomethane. With this method sharp, well-resolved chromatographic peaks were obtained with no interferences. Inclusion of deuterated analogues enabled accurate quantification. Good linearity, recoveries and precision were achieved. Differences observed between the SCFA profiles of normal subjects and patients with cystic fibrosis indicate the potential of this new technique for clinical studies. 2-Methylbutyric acid was found in all faecal samples. Few have reported this before.