Stray radiant energy test method in spectrophotometry based on direct transmittance spectrometry

Abstract

A sample-based stray radiant energy (SRE) test method in spectrophotometry which takes the attenuation of the SRE by the sample into account is described. The proposed test method allows the SRE transmittance of the sample and the true relative SRE level of the spectrophotometer to be determined by measuring the absorbances of concentrated food dye samples such that the monochromatic transmittances are much less than the relative SRE level. The proposed test method was applied to a double-beam spectrophotometer, i.e., a Shimadzu 260 instrument, at two slit-heights while maintaining the spectral slit-width and wavelength constant. The ensuing SRE values were compared with those obtained previously via transmittance ratio spectrometry on the same food dye samples under identical instrumental conditions.