Apparatus and method for spectrophotometric analysis of a material in a moving process stream

A method of spectrophotometric analysis of material in a moving process stream wherein the material is directed into an observation chamber within a sample cell and exposed to a radiation beam suitable for spectrophotometric purposes, said

• (a) providing a radiation source and a radiation detector contained within a first compartment;
• (b) providing a second compartment environmentally isolated from said first compartment and within which said sample cell is contained;
• (c) providing reflective means positioned within said second compartment for receiving the radiation beam from said first compartment, directing said radiation beam through said sample cell and the material to be analyzed contained therein, and directing the radiation beam back into the second compartment and the radiation detector positioned therein;
• (d) maintaining the environment within said second compartment within a range acceptable for radiation analysis of the material within the sample cell;
• (e) diverting said radiation beam from passage through said material while continuing the passage of the beam through the environment of the second compartment;
• (f) directing the diverted beam to the radiation detector;
• and
• (g) determining a reference spectra within the same environment as the sample cell.