Errors in the Analysis of Minor Components within Environmental Samples Caused by the Physical Matrix Effect: Implications for Automated Analysis and Standardised Methods

Abstract

It is generally agreed that for the purposes of performing analytical determinations, the highest accuracy calibration standards are those prepared by mass (gravimetrically) as opposed to by volume (volumetrically). However, the use of gravimetrically prepared standards to calibrate analytical techniques that rely on fixed volume injections can cause systematic errors. These errors can occur even when the analytical technique does not suffer from a chemical matrix interference. The physical matrix of the sample has been shown to be the cause of these errors. This effect is demonstrated experimentally for the analysis of minor components within two environmental samples. Proposals are offered for methods to overcome this ‘physical matrix effect’.

Keywords:

• Physical matrix
• Automated analysis
• Gravimetrically
• Volumetrically

Acknowledgments

This work was funded by the UK DTI National Measurement System's Valid Analytical Measurement Programme.