Standard addition

The standard addition method ( Standardzumischmethode ) is a way to create a calibration for quantitative determinations in analytical chemistry. The name refers to the addition of a standard ( or analyte ) for the analysis sample.

Typically, a calibration function is created for calibration. For this, a series of solutions of different concentrations of an artificial stock solution is usually made ( dilution series ). The calibration solutions and all samples are each measured once. The analyte concentration in the sample can be calculated by the calibration function.

In the standard addition method, however, each sample is repeatedly added to a certain amount of analyte, and the sample is measured after each addition. With growth of the analyte signal is determined. By linear regression of the concentration of the analyte can be calculated in the original sample. The calibration is thus generated from the specimen by addition of the analyte ( " spike "). In the optimal case, the added proportion of the analyte in the same range as should be the concentration of analyte in the original sample, which requires some prior knowledge of the sample content.

With the standard addition method instrumental error and matrix effects (ie, effects of the constituents of a sample can not be analyzed, see sample for analysis ) should be minimized, especially for measurements at low concentration ranges ( trace analysis, studies of recovery rates for method validation ). The standard addition method is advantageous when the analyte is strongly influenced by the sample matrix ( esp. for complex matrices ). Then would have to stand for the normal calibration matrix matched calibration standards available, which is usually not possible. Also, the method of the internal standard is only limited for complex matrices.

The method of standard addition requires a linear response of the analytical method, and the exact controllability of the analyte as a standard accessory. The advantage of the standard addition is that matrix effects can be corrected. Disadvantages are the higher labor costs and possible problems in the linear range of the analytical method is exceeded.

Swell

• DIN 32633: " addition method "

• Analytical Chemistry