A new anthracenyl-imino-glucosyl conjugate (L) selectively senses Hg2+ by turn-on fluorescence with a 13 ± 1 fold enhancement by forming a 2 : 1 complex in pH 5 to 10 even in the presence of several biologically and ecologically relevant metal ions, with a 25 ± 2% fluorescence enhancement at the EPA limit of 2 ppb. L is equally sensitive towards Hg2+ in the presence of albumin proteins and in blood serum and milk. © 2011 The Royal Society of Chemistry.