Standards & calibration
Calibration of the complete analytical process is of paramount importance when conducting quantitative studies. For TD analysis, additional considerations should be made regarding the loading of standards to be representative of samples, with a variety of tools available to support this.
In addition to gas standards for both canister and tube-based methods, a number of products have been developed to support laboratories with their calibration and validation:
- The Calibration Solution Loading Rig (CSLR) was developed to optimise the introduction of liquid standards onto sorbent tubes, by transferring the standard in a flow of gas.
- Check-standards are sorbent tubes pre-loaded with a suite of analytes that can be used to check instrument performance during set-up or troubleshooting.
- CRS tubes are loaded with a certified level of analytes and are designed to validate calibration for QA, as described in international standards. They are supplied with a shipping blank, and example chromatograms of the sample and shipping blank.
- Tubes for liquid calibration contain a short bed of sorbent for analysts wishing to inject a liquid standard directly onto the sorbent tube, rather than loading the tube using a flow of gas (e.g. with the CSLR).
Proficiency testing schemes
Proficiency testing (PT) schemes are available to laboratories seeking to demonstrate quality to regulatory agencies, accreditation bodies and customers. One of the most popular PT schemes for air monitoring – with over 350 participating laboratories – is offered by LGC Standards in partnership with the UK Health & Safety Executive.
Participating laboratories are provided with spiked tubes for analysis, with results being passed to the PT scheme organiser. A report is then compiled detailing how the results of individual laboratories compare against the accepted values from other participating laboratories.