Not all methods, the equipment and qualification allow to measure chemical purity of copper equally. Some methods cannot measure some of elements. At LMS + AES (with current limits of measuring) we do not see any impurities, except for Fe and Ag when they are not less than 0.1 ppm and assume the level fixed in parameters of technology and in our standards. Other methods, with the best limits of detection, will have higher results. That is not automatically fair for not our copper. Purity (as quality) does not vary there are variations of the result of measuring expressed in percentages.
We have own technology allowing to predict and supervise a chemical compound. Moreover, being based on result LMS of our product, we can tell results which should be been by other method and the equipment at the qualified measurement. It is no wonder that "metals basis 99.999 %" by LMS can be above "metals basis 99.9999 %" by GDMS. For example, the certificate # Т 10-28. The result very good, but also it can be better. Even serious laboratories insufficiently precisely can measure our quality. It can be explained by a methods and equipment, by materials for preparation of the copper sample and by qualification of the personnel. There are also other moments.
Acknowledgement of quality of our product is the electric conduction independent of methods of the analysis. It is 104-105 % IACS for superpure copper. Also our copper was put to the test to losses on reflection in the Institute of Applied Physics of the Russian Academy of Sciences where also copper had excellent characteristics at 0-300К. At cryogenic temperatures noticeably even presence of the minimal impurity.
You can look at photos, certificates and other documents under corresponding reference >>