Abstract: A method and apparatus are provided for rapidly and accurately processing the chemical composition of a molten metal bath within a furnace. The apparatus includes a robotically-controlled probe which operates to obtain a sample from any predetermined depth of the vessel. The probe is moved from the vessel to a thermostabilized atomic emission spectrometer in nearby proximity to the vessel wherein a part of the probe containing the sample is joined with an upper chamber housing to form an excitation chamber. Within the excitation chamber, the optical emission spectrum of the sample is excited by an excitation source. The optical spectrum is transmitted to an analyzer where the elemental concentration of the sample is determined. Immediately responsive to this analysis, adjustments are made in processing to achieve the target grade of steel.