Any information on EnviroLyzer series II from Applitek

I am doing some research on various online wet chemistry analyzers to determine the nitrate concentration in the drinking water. I came across a product line called EnviroLyzer series II. I was not able to find any information about what process does this instrument used, or what is the theory of operation behind this instrument. Does this instrument use one of the two known methods, cadmium reduction, hydrazine reduction, or something else? Is there anyone who has one in their plant? If so, could you provide me with some information that I could share with others? Thanks.