Abstract: A method of chemical analysis of a sample in solution in which the optical density of the solution is modified by addition of a dye to the solution, and the modified optical density is utilized in determining the concentration of the sample in the solution. That determination is effected by measuring the optical density of the dyed solution and applying a value thereto, and then comparing that value with a predetermined value which corresponds to a particular sample concentration. The actual sample concentration is assigned a value in accordance with the results of that comparison, and that assigned value is employed in determining the concentration of a particular element in the sample by spectral analysis. Apparatus for carrying out the method includes a first spectrophotometer for determining the optical density of the sample solution, and a second spectrophotometer for applying a value to the concentration of the element of interest in the atomized sample.