A compact diode laser/fiber-optic Raman spectrometer is used for quantitative detection of environmentally important dyes. This system is based on diode laser excitation at 782 nm, fiber-optic probe technology, an imaging spectrometer, and a state-of-the-art scientific CCD camera. The dyes studied include trypan blue, acid black 1, acid blue 40, and basic blue 7. Detection sensitivities (at rms S/N = 2) ranged from 0.2 ppm (3.24 x 10-7 M) for acid black 1, to 25 ppm (4.86 x 10-5 M) for basic blue 7.
Daniel A. Gilmore, Donald Gurka, and M. Bonner Denton, "Quantitative Detection of Environmentally Important Dyes Using Diode Laser/Fiber-Optic Raman Spectroscopy," Appl. Spectrosc. 49, 508-512 (1995)