A　robust　method　based　on　solid-phase　extraction　(SPE)　followed　by　ultra　high　pressure　liquid　chromatography　(with　trade　name　of　Ultra　Performance　Liquid　Chromatography:　UPLC;　Waters,　Milford,　MA,　USA)　is　proposed　for　the　determination　of　five　derivatives　of　N-acylhomoserine　lactones　(AHLs)　that　play　a　biological　role　as　signal　molecules　of　several　gram-negative　bacteria.　Different　commercial　SPE　cartridges　were　tested　for　sample　extraction,　clean-up　and　preconcentration.　Since　the　sample　matrix　was　a　complex　growth　media,　careful　optimization　of　the　SPE　with　respect　to　washing　procedure,　elution　solvent　and　sample　solvent　was　necessary.　No　sample　loss　was　observed　when　up　to　100mL　spiked　full　media　was　added　onto　the　cartridge.　Applying　UPLC　for　the　determination　of　AHLs,　the　performance　characteristics　of　the　method　showed　good　separation　efficiency　and　high　speed.　In　order　to　demonstrate　the　applicability　of　the　method,　supernatants　with　the　known　AHL　producer　Burkholderia　cepacia　LA3　grown　in　different　media　were　investigated.　Additionally,　the　method　was　successfully　used　for　the　degradation/uptake　study　of　AHLs　from　a　liquid　matrix　in　which　barley　was　grown　under　controlled　condition.　(c)　2006　Elsevier　B.V.　All　rights　reserved.