Chapter 4
Liquid Chromatography/Mass Spectrometry
(LC/MS) for the Detection and Quantification
ofN-Acyl-L-Homoserine Lactones (AHLs)
and 4-Hydroxy-2-Alkylquinolines (HAQs)
Franc ̧ois Le ́pine, Sylvain Milot, Marie-Christine Groleau, and Eric De ́ziel
Abstract
High-performance liquid chromatography (HPLC) coupled in-line with mass spectrometry (MS) permits
rapid and specific identification and quantification ofN-acyl-L-homoserine lactones (AHLs) and 4-
hydroxy-2-alkylquinolines (HAQs). We are presenting here methods for the analysis of these molecules
directly from biological samples using LC/MS.
Key wordsBacteria, Quorum sensing, Acyl-homoserine lactone, 4-Hydroxy-2-alkylquinoline, Anal-
ysis, Quantification, Mass spectrometry, Liquid chromatography1 Introduction
Most Gram-negative bacteria produceN-acyl-L-homoserine lac-
tones (AHLs), such asN-(3-oxododecanoyl)-L-homoserine lac-
tone (3-oxo-C 12 -HSL) and N-butanoyl-L-homoserine lactone
(C 4 -HSL) forPseudomonas aeruginosa[1, 2]. A few species, such
asP. aeruginosa,Burkholderia pseudomallei, andBurkholderia thai-
landensisalso release a number of 4-hydroxy-2-alkylquinolines
(HAQs), also known as 2-alkyl-4-quinolones [3–6] and derivatives,
such as 3-methyl analogs (HMAQs).
Although bioassays are essential for screening and for rapid
qualitative determination of quorum-sensing signaling molecules,
more precise and sensitive methods are required to provide defini-
tive confirmation of their presence and allow formal structural
confirmation and accurate quantification. Because of the very
large number of structurally related signaling molecules, a prelimi-
nary separation is required using high-performance liquid chroma-
tography (HPLC). Identification and quantification are then
performed by mass spectrometry coupled in-line with the HPLC.Livia Leoni and Giordano Rampioni (eds.),Quorum Sensing: Methods and Protocols, Methods in Molecular Biology,
vol. 1673,https://doi.org/10.1007/978-1-4939-7309-5_4,©Springer Science+Business Media LLC 2018
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