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Laser Excited Atomic Fluorescence for Measuring Organomanganese and Organo-tin
Compounds in Liquid Chromatography Column Eluents

Walton et al. [17] extended the method further, and incorporated a monochromator and photomultiplier
as the sensor, so that the device was truly a tandem system, incorporating a liquid chromatograph and a
spectrometer. Three different modes were investigated, two utilizing pulsed laser excitation (one
measuring fluorescent light emitted from the flame at right angles to the laser beam and the other
measuring light reflected back along the line of the laser beam) the third using a high-energy UV light
source the emitted light being measured normal to the UV incident beam. The excimer pump laser was
the Tachistom Model 800XR, with an output at 308 nm. The dye laser was the Molectron DL 19P
(frequency doubled output beam), the output energy/pulse for manganese at 280 nm (Rhodamine dye)
was 8 µJ, and for tin at 300 nm (Rhodamine 610 dye) was 5 µJ. The continuum light source was a
xenon arc lamp, Model VIXX 300 UV, having an output of 300 W. The flame was an air-acetylene
premixed burner, having a 10 mm path length with a pneumatic nebulizer uptake at I ml/min for
manganese solutions, and 4.0 ml/min for tin solutions.

The separation of the organomanganese species was carried out on a C8 reversed phase column, using a
mixture of 65% methanol and 35% aqueous 0.05 M ammonium acetate buffer (pH 4.0), at a flow rate of
I ml/min. The organotin mixtures were separated on a strong cation exchange column, with a mobile
phase consisting of 80% methanol and 20% aqueous 0.2 M ammonium acetate buffer (pH 4.0), at a
flow rate of 4 ml/min. Both analytical columns were protected by small guard columns, and the volume
of sample placed on either column was 20 µ1. The minimum level of detection for organomanganese
species was claimed to range from 8 to 22 pg.

The laser-excited atomic fluorescence spectrometer certainly increased the overall sensitivity of the
apparatus, and at the same time identified, unambiguously, the metal element that is present. The
organomanganese