How to determine chemical purity

Purity of copper is defined by the contents of the basic substance and expressed in percentages defined as a difference between 100 % and the sum of supervised impurities.

Supervised impurities - the list of elements are measured in the sample for definition of purity.

The RESULT of the measurement may vary depending on the analysis methods, equipment and qualifications. Purity does not change.

Standards

Supervised impurities can be defined by various standards or specifications.

As a rule, not only the list of controlled impurities and their total limit content is determined, but also the limit content of certain groups of them or each of them. Different elements affect the characteristics differently and, not only the sum of the impurities is important, but also their “portrait” (how many and what element).

Chemical purity and compound are indicated according to  the most known standards are GOST 859-2001 (Russia), ASTM B170 (USA).

TECHNOLOGY  AND  TEST  METHODS

The technology used allows us to produce, predict and control the chemical composition with a purity higher than 5N. The material was tested in various leading laboratories in Russia, the USA and China.

Not all methods, the equipment and qualification allow to measure  chemical purity of copper equally. Especially it concerns purity of 5N+ and above. Some methods and laboratories cannot measure certain elements or test exactly, like they are real.

Analysis methods included Laser Mass Spectrometry (LMS), Atomic Emission Spectrometry (AES), Spark Source Mass Spectrometry (SSMS), Glow Discharge Mass Spectrometry (GDMS). 

COMMENTS  ON  METHODS

LMS+AES (Institute of Inorganic Chemistry of the Siberian Branch of the Russian Academy of Sciences, Russia) are limited by methods and the equipment: excluding Fe and Ag, all impurities are always is Detection Limit of methods and the equipment, including metals and metalloids not entering into  ASTM B170 (limits are <0.08 - <0.2 depending on an element).
Oxygen is measured and counted "< 2 ppm" as LMS Detection Limit of the current equipment. In reality, oxygen can be <0.05 - <0.1 - <1ppm.  Our technology is able to make it. It is necessary to find and use the equipment  capable of  such measuring.  Needed  Detection Limit  is <0.01ppm.

SSMS and GDMS have deeper detection limits for many impurities, but still insufficient to measure our quality. The methods have difficulties with measuring oxygen, sulfur, and also with the accuracy of measuring sometimes some other impurities with respect to how they can be / are in reality. Some elements are difficult to measure accurately with the GDMS method, at least in its standard version. They are more correctly tested using the SSMS method, but it also has its own specifics.