A simple fluorimeter which uses a light-emitting diode as a source of excitation and a photodiode as a detector has been constructed and evaluated. The exceptional stability of both the detector and the source make it possible to make concentration measurements by fluorimetry with a precision of at least 0.002%. Furthermore, the system exhibited excellent linear dynamic range and a limit of detection of 20 ng/L for the dye Oxazine 720 in methanol.
B. W. Smith, B. T. Jones, and J. D. Winefordner, "High-Precision Fluorimetry with a Light-Emitting Diode Source," Appl. Spectrosc. 42, 1469-1472 (1988)