Effect of Matrix Material on Laser induced Elemental Spectral Emission

The magnitude of the suppression of spectral emission of metallic elements by organic material in sampling and excitation with a ruby laser microprobe was studied in model systems in which intensities of spectral lines of silver and magnesium were measured in relation to the presence of bovine serum albumin and human serum. The silver emission was also investigated in the presence of sucrose, sodium acetate, and sodium sulfate. The sodium acetate and sulfate were included to represent a combined Inorganic-organic compound and a totally inorganic compound. Methyl blue was used in an attempt to intensify the laser energy absorption by the sample, but it failed to increase, and in higher concentrations decreased, the silver emission. For all matrix materials increasing concentrations above a threshold value diminished the emissions. The threshold level varied with the nature of the emitting element and of the matrix. It was observed that, at constant laser energy, the presence of increasing concentrations of matrix progressively decreased the amount of sample vaporized.