To perform long-path absorbance measurements for liquid samples, a luminescence detector cell must act as an optical fiber or waveguide. Otherwise, excessive noise results. And if the cell is to function as a liquid core waveguide, it must be made of material with a lower refractive index than the liquid surrounding it. In the past, systems have used materials such as carbon disulfide in a glass tube or ethanol in a fluorinated ethylene-propylene copolymer.

Now a team from Texas Tech University in Lubbock reports the use of an amorphous fluoropolymer, Teflon AF, in liquid core waveguide cells. The transverse illumination technique reduces the need for monochromators and focusing optics, and enables efficient fiber optic coupling of remotely located detectors. The researchers published their findings in the April 1 issue of Analytical Chemistry.