The use of polarizers to improve detection limits in fluorimetric analysis

The use of variously-oriented film polarizers to reduce scattered light interference in fluorimetric analysis is reported. Single horizontally-oriented polarizers in the excitation beam (to obtain fluorescence spectra) or the emission beam (to obtain excitation spectra) are efficient at removing first-order Rayleigh scattered light signals. Crossed polarizers are necessary to remove substantial second-order signals. With the aid of polarizers, fluorimetric detection limits can be considerably improved, even when excitation and emission maxima are well separated, and when deproteinized blood plasma is analyzed. Polarizers are also effective in reducing scattered light signals from macromolecular solutes.