title: A simple and robust set-up for on-column sample preconcentration--nano-liquid chromatography--electrospray ionization mass spectrometry for the analysis of N-acylhomoserine lactones.
abstract: A simple method for the simultaneous, rapid and sensitive determination of N-acylhomoserine lactone signaling molecules in bacterial isolates, without prior sample preconcentration and with minimal sample cleanup, is presented. The analysis relies on the combination of analyte preconcentration and separation on a single device: a relatively large sample volume (1-5 microL) is directly loaded onto a laboratory-made, miniaturized (75 microm i. d.) reverse phase nano-liquid chromatography column, connected on-line to a microelectrospray-ionization ion trap mass spectrometer. In a first step the analyte is adsorbed (and so concentrated) at the beginning of the column, and is eluted and selectively separated in a second step by the organic mobile phase. Sample preconcentration follows the mechanisms of solid phase extraction on a nano-scale, while separation takes place according to classical liquid chromatography separation principles. The columns can be manufactured easily, are simply connected, and used with minimal solvent amounts; this makes this method extremely robust and cost-effective. The analytical setup was found to be routinely quantitative down to a concentration of 10 ng/mL (corresponding to a total analyte amount of 10 pg or ca. 50 fmol). The limit of detection was reached at 1 ng/mL (1 pg, ca. 5 fmol). Compared to the classical AHL analysis of bacterial cultures with biosensors, where selectivity and sensitivity is often limited, this rapid analytical technique is a substantial qualitative and quantitative improvement. Two unsubstituted N-acylhomoserine lactones could be identified and quantified from a Burkholderia cepacia culture supernatant in a chloroform extract.
authors.affiliation: Institute of Ecological Chemistry, GSF National Research Center for Environment and Health, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany.
authors.forename: Moritz
authors.initials: M
authors.lastname: Frommberger
authors.forename: Philippe
authors.initials: P
authors.lastname: Schmitt-Kopplin
authors.forename: Guichen
authors.initials: G
authors.lastname: Ping
authors.forename: Heinz
authors.initials: H
authors.lastname: Frisch
authors.forename: Michael
authors.initials: M
authors.lastname: Schmid
authors.forename: Yukui
authors.initials: Y
authors.lastname: Zhang
authors.forename: Anton
authors.initials: A
authors.lastname: Hartmann
authors.forename: Antonius
authors.initials: A
authors.lastname: Kettrup
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000032:analysis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D007783:Lactones / Q000032:analysis* / Q000737:chemistry*; D015394:Molecular Structure; D036103:Nanotechnology / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D007783:Lactones; D015107:4-Butyrolactone