Occurrence of <i>N</i>-Acyl Homoserine Lactones in Extracts of Bacterial Strain of <i>Pseudomonas aeruginosa</i> and in Sputum Sample Evaluated by Gas Chromatography–Mass Spectrometry

Abstract

This study presents a fast, accurate and sensitive technique using gas chromatography-mass spectrometry (GC-MS) for the identification and quantification of <i>N</i>-acyl homoserine lactones (AHLs) in the extracts of bacterial strain of <i>Pseudomonas aeruginosa</i> and sputum sample of a cystic fibrosis patient. This method involves direct separation and determination of AHLs by using GC-MS as simultaneous separation and characterization of AHLs were possible without any prior derivatiza-tion. Electron ionization resulted in a common fragmentation pattern with the most common fragment ion at m/z 143 and other minor peaks at 73, 57 and 43. The limit of detection for <i>N</i>-butanoyl, <i>N</i>-hexanoyl, <i>N</i>-octanoyl, <i>N</i>-decanoyl, <i>N</i>-dodecanoyl and <i>N</i>-tetradecanoyl homoserine lactones was 2.14, 3.59, 2.71, 2.10, 2.45 and 2.34 µg/L, respectively. The presence of AHLs in the culture of P. aeruginosa strain and spu-tum of a cystic fibrosis patient was achieved in selected ion monitoring (SIM) mode by using the prominent fragment at m/z 143.