LASER-INDUCED FLUORESCENCE DETECTION OF RHODAMINE-6G AT 6 X 10-15 M

Abstract

We have demonstrated sensitive fluorescence detection of rhodamine-6G in aqueous solutions down to approximately 10(-15) M with a detection limit of 6 x 10(-15) M. The working curve was observed to be linear over four orders of magnitude and could be extended to higher concentrations. Single molecules of rhodamine-6G had a transit time of 1.8 ms through the 11 pL probe volume. At 2 x 10(-14) M, the probability of a molecule being in the 11 pL probe volume is approximately 0.1. Analysis of the data indicates that the signal-to-noise for the detection of a single molecule of rhodamine-6G is approximately 1.