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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.
CHEMICAL  PURITY  and    TRACE  OF  IMPURITIES



Analysis of our Copper requires methods appropriate to this level of purity, very good preparation of equipment, super-quality and super-pure materials and instruments (chemical substances, cutters and other work tools) for preparation of the copper sample for analysis, and  the highest qualification level of the laboratory personnel.

Chemical purity, maximum impurity content, current grades / grades are determined according to the methods and tests performed:

  • Basic Grade - basic quality. The process parameters were studied and established to achieve a quality of at least Cu OF 5N5 according to GOST 859-2001 and ASTM B170 (USA).There are difficulties in measuring this level with available methods and laboratories.
  • Extra Grade - additional quality, an experimental process to achieve OF 6N and above according to GOST 859-2001, ASTM B170. There are no accessible methods and laboratories capable of the required level of measurement.

Max- and Typical- impurities by SSMS+GDMS are   not   for   the   best   tests,   some   possible inaccuracies and small possible mistakes were taken into account and added, but still  they  are  for  the  sufficiently  qualified  measurement. For  Min of impurities there is need for the highest level of testing, also possibly by other methods appropriate to this level. Limits of sensitivity " <x - <0.00x " were considered (were subtracted from 100 %) at calculation of purity as corresponding quantity of impurities.

Wishes of the customer to additional restrictions of impurities besides our specified current standards can be considered, if it is possible to fulfil it.  Own technology, an opportunity of achievement of the specified parameters.

Chemical purity and traces of impurities :
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