93Expanded programs4. Press OK to confirm.Note: If a Favorite Program is deleted, it will stay in the UserPrograms or Stored Programs.Note: If the stored program is deleted in User Programs, it will alsobe deleted in Favorites Programs.6.3 Standard Addition - monitoring/checking resultsThe accuracy of readings (their correspondence with the actualconcentration of the analyte in the sample) and their precision(correspondence of the reading results obtained from severalsamples containing the same concentration of the test analyte)can be determined or improved using the standard additionmethodThis method (also known as standard-addition or spiking) servesto detect sample-specific faults:• The analysis was compromised by substances orinterferences in the sample (sample matrix effect),• defective measuring device,• impure reagents.Method:Add a defined quantity (concentration) of the substance to betested to the sample as a standard solution. The detection rate(concentration of the added standard solution) should be close to100 %.Detection rate =Reading of successful standard additionExpanded value after successful standardadditionDetection rate Conclusion100 % Probability that the reading results are correctis high.≠ 100 %Assumption: The analysis was compromisedby substances or interferences in the sample(sample matrix effect)Test to determine whether a sample matrixeffect is present:Use distilled water instead of the sample. Addstandard solution as described in theprocedure.Detection rate Conclusion100 %Ions in the sample areinterfering with theanalysis, causing falseresults to be obtained.≠ 100 % No interference ions.
