A fiber optic sensor device for detecting the presence of a chromophoric
compound in a biological fluid is disclosed. The fiber optic sensor
device includes at least one fiber optic member having an unclad portion,
the fiber optic member having a proximal end and a distal end for
transmitting light energy of a determinable wavelength, a light source
means for generating light energy of determinable wavelength, said light
source means operatively associated with a measuring means such that said
light energy passes through said measuring means and said fiber optic
member to the biological fluid, and measuring means operatively
associated with said fiber optic member and said light source, for
measuring the difference between said light energy generated by said
light source and light reflected from the distal end of the fiber optic
member, wherein the difference is related to the light absorbed by the
chromophoric compound and indicative of the concentration of the
chromophoric compound present in the biological fluid.