ABSTRACT
The first step in many laboratory tests is to separate the material of interest from other substances. This may be accomplished through extraction, filtration, and centrifugation. Another step is derivatization, in which the substance of interest is chemically altered through addition of reagents to change it into a substance which is easily measured. For example, one method for measuring glucose is to add otoluidine which, under proper conditions, forms a green-colored solution with an absorption maximum at 630 nm. Separation and derivatization both improve the specificity required of good tests.
