Systematic error arising from 'sequential' standard addition calibrations. 2. Determination of analyte mass fraction in blank solutions.
The use of a sequential standard addition calibration (S-SAC) can introduce systematic errors into measurements results. Whilst this error for the determination of blank-corrected solutions has previously been described, no similar treatment has been available for the quantification of analyte mass fraction in blank solutions--a crucial first step in any analytical procedure. This paper presents the theory describing the measurement of blank solutions using S-SAC, derives the correction that needs to be applied following analysis, and demonstrates the systematic error that occurs if this correction is not applied. The relative magnitudes of this bias and the precision of extrapolated measurements values are also considered.
Brown
Richard J C
RJ
Analytical Science Team, National Physical Laboratory, Teddington, Middlesex TW11 0LW, UK. richard.brown@npl.co.uk