DIN Standards Committee Materials Testing
Chemical analysis - Methods of Standard addition - Procedure, evaluation, with CD-ROM
Chemische Analytik - Verfahren der Standardaddition - Verfahren, Auswertung, mit CD-ROM
This document has been prepared by NA 062-08-15 AA "Grundlagen der analytischen Atomspektroskopie" ("Basic principles of analytical atomic spectroscopy") at the Materials Testing Standards Committee (NMP). This document specifies the method of standard addition. Standard addition allows for calibration of an analysis method using the sample to be analysed. Standard addition is used for determination of the content of an analyte, - when differences in the composition of the sample matrix and the standard(s) strongly affect the precision of results; - when no matrix-adapted standards are available; - when the content of the analytes is below the limit of quantification. The gravimetric approach reduces the experimental complexity and improves measuring uncertainty. Through additional application of an interior standard the contributions to measuring uncertainty by - fluctuations of the measuring signal, - losses during sample preparation as well as - changes in the sample in the course of storage and/or handling are significantly reduced. The application of this standard is subjected to meeting the following prerequisites: - measuring values y i corrected for blank value and background; - linear correlation between the measuring size and content; - a residual standard deviation syx that is independent of y; - a homogenously dividable analysis sample; - precise dosability of the analyte in the form of the added standard. The sensitivity of the analysis method (pitch (Alpha)1 of the linear calibration function) shall be independent of the analyte species and the added standard, and shall not be disrupted by other influences (for instance absorption). This standard is to be used with caution when even one of these prerequisites is not met.