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Answer:

The assigned content of a CRS assay is provided When required by the prescribed test and/or assay of the corresponding Ph. Eur. text, the content a CRS is given in the leaflet available on ourin the Ph. Eur. reference standards database.

For impurity CRSs used for quantification in the related substances test of the corresponding Ph. Eur. monograph, the content can be assumed to be 100%, unless otherwise indicated in the leaflet.

In all other cases, no value is assigned and no assumption can be made on the purity or content of the reference standard CRS database.
If a CRS has no assigned content, this should in no case be interpreted as if the content were 100 per cent. For assay purposes, the content explicitly assigned must be used.
However, when an impurity reference standard is used in a related substances test for the control of an impurity and if no assigned content is indicated, the purity of the reference standard, for the purpose of this estimation, is considered to be 100 per cent.