Impurity Analyses – Clear Fused Quartz (CFQ) vs. Suprasil (Synthetic Quartz)
Clear Fused Quartz (CFQ) is purified from naturally occurring quartz so the existence of certain material radicals from mining is inevitable. Chemical impurity analysis results for CFQ are shown below:
Table 1: Impurity Analysis for Clear Fused Quartz (unit: ppm in weight)
Due to technological advancements the sensitivity of EPR has gradually increased. The direct result is that certain high Q cavities will pick up the signal from these impurities, especially in tubes of over 4 mm OD. In this case we recommend switching to Suprasil® EPR products which are made of synthetic material and suppress major impurity contents shown in Table 1 by the average of 2 orders of magnitude. Impurity analysis test results for Suprasil® are shown below:
Table 2: Impurity Analysis for Suprasil Quartz (unit: ppm in weight)
Important Note: Product numbers that include “PQ” belong to our Precision Tube Family with an OD and ID tolerance of ±0.013 mm. Those with “SQ” are not Precision and their OD and ID may vary as much as ±0.4 mm. For EPR experiments that must estimate electron spin density and/or produce highly repeatable signal amplitude between different runs we strongly recommend our Precision EPR Tube.