Filters are typically manufactured to meet specifications for removal of particles to result in defined solution purity characteristics. For example, a 0.1 µm rated pore size filter is typically defined as capable of removing 99.98% of particles >0.1 µm from a liquid. The pores present on the surface of the filter, however, may be much larger or smaller than 0.1 µm.

Maximum peak resolution in alpha spectrometry requires a uniform filter surface to ensure a uniform deposition of the rare earth fluoride precipitate. Filters which allow significant penetration of the precipitated alpha emitting nuclides below the surface of the filter will produce alpha spectra with poor resolution due to self attenuation.

Recently reported resolution quality concerns indicate that manufacturing specifications and quality control procedures of many filter suppliers may not address the specific needs of alpha spectrometry. Eichrom’s line of Resolve™ Filters (0.1 µm polyethylene, 25 mm diameter) are manufactured to specifications which consistently provide high quality alpha spectra.