blank solution

a solution that does not contain a detectable amount of the analyte of interest. The blank solution is typically used for calibration purposes. Depending on its purpose the following blank solutions can be defined:

• Calibration blank (the solution used for creating the zero concentration point of the calibration graph; this solution contains only the diluent used for making the standard solution)
• Reagent blank (a blank solution that contains the reagents used to dissolve the samples such as acids used for digestion; the reading for this solution is typically substracted from sample readings)
• Method blank (a blank solution that has been handled similar to a sample, and to which the same reagents have been added, that had contact to the same type of vessels and that was treated by a similar procedure. This solution than is handled to monitor any type of contamination taking place with the method used.

The correct treatment of the analytical result for the blank solution does have a significant effect on the correctness of analytical results, especially for samples having analyte concentrations close to the limit of quantitation. Especially the measurement of the reagent and method blank must be well differentiated from the baseline correction.