Specification

Certipur^® Certified Reference Material

Application and correct use:  Thisreferencematerial is intended for use as a calibration standardfor

pH instruments or pH electrodes or as a control sample for measuring the pH value. The pH value is strongly dependent on the temperature. It is therefore necessary to keep the temperature constant within the measurement. Details concerning the nature of any hazard and appropriate precautions to be taken are provided in the material safety data sheet.

Expanded uncertainty UCRM:          The expanded uncertainty UCRMis calculated as UCRM= k·uCRM, where k = 2

is the coverage factor for a 95% coverage probability and uCRMis the combined standard uncertainty in accordance to ISO Guide 34.

Further information:

The combined standard uncertainty uCRMis obtained from the standard uncertainties of the characterisation, the homogeneityand the stability. uCharacterisation              is the uncertainty in accordance to DIN EN ISO/IEC 17025

which includes the contributions of the primaryreference material and the measuring system.

uHomogeneity              is the between-bottle variation in accordance to

ISO Guide 34.The assessment of homogeneity is performed by analysis of a representative number of systematically chosen sample units

uStability                      is the uncertainty obtained from short-term and long-term stability in accordanceto ISO Guide 34.Thestability studies are the basis for the quantification of the minimum shelf life of this reference material for the unopened bottle.