From 2007.igem.org

AHL assay Standard protocol

prepare overnight culture
(3 tubes for AHL-activated promoters, 2 tubes for each - positive and negative -control)
take 30 ul of the overnight culture into LB + Antibiotics (⇒fresh culture)
incubate the fresh culture until the observed OD reaches around 0.80.
prepare and add AHL mixture
incubation for 2 hours
FLA measurements for GFP expression