Hexagon

Calibration and Verification standards

Altus Science is a Certified Reference Material (CRM) provider, focusing on Total Organic Carbon (TOC), providing Calibration and Verification standards for all makes of TOC analysers. A full list of products available can be found here.

Calibration in measurement technology and metrology is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. No need to say that the quality of delivered data is only as good as the standards used to calibrate the analytical instrumentation. Therefore calibration should always be based on ISO Guide 34 accredited CRMs.

There are a few basics to consider when it comes to calibration:

  • The highest calibration standard should always be above the TOC level in your samples in order to ensure that your samples will lie within the demonstrated linear range of the instrument and method.
  • Verify the calibration on a regular basis with multiple standards within the linear range.
  • Use verification standards that are prepared independently from the calibration standards, ideally using a different compound.  

Verification is intended to:

  • measure the accuracy of a calibration procedure 
  • indicate possible calibration drift

When verifying calibration accuracy, the standard should be prepared separately from the standards used for calibration, ideally with a different compound, in order to have a standard that is fully independent of the calibration. If verification is performed as an indicator of calibration drift, the standard used should be at the same concentration as the standard used during calibration.

Daily QC standards are used to demonstrate that the system is in control and are usually analysed with every batch of samples. The standards should lie in the same concentration range as the actual samples. If internally prepared standards are used for routine quality control, we recommend periodic use of an externally supplied certified reference material for verification purposes.