Determination of bromine in selected polymer materials by a wavelength-dispersive X-ray fluorescence spectrometric method — Critical thickness problem and solutions

• The critical thickness for Br-Kα line in light matrix is up to several millimeters.
• The Br in the measured volume was determinated for the thin samples.
• The BaCO3 was added to the sample to reduce the Br critical thickness value.
• A tube Rayleigh line was used for correction of the Br critical thickness impact.
• The Br-Lβ line may be used when the Br-Kα critical thickness value is too high.

The purpose of this study was to develop an accurate method for the determination of bromine in polymer materials using X-ray fluorescence spectrometry when the thickness of the sample is less than the bromine critical thickness (tc) value. This is particularly important for analyzing compliance with the Restriction of Hazardous Substances Directive. Mathematically and experimentally estimated tc values in polyethylene and cellulose matrixes were up to several millimeters. Four methods were developed to obtain an accurate result. These methods include the addition of an element with a high mass absorption coefficient, the measurement of the total bromine contained in a defined volume of the sample, the exploitation of tube-Rayleigh line intensities and using the Br-Lβ line.