White calibration methods based on gradient techniques as a modern approach to quantitative flow analysis

In the paper the concept of a “white calibration method” is proposed, that is, one that is consistent with the three basic attributes of a white analytical method: environmentally friendly (green), analytically reliable (red), and operationally effective (blue). It was assumed that these conditions can be met when the calibration is of complex nature and implemented in gradient flow analysis. As an example, three methods based on the processes of sample-to-standard combination, dilution and internal standardization are presented. On the basis of experimental results, their characterization was made and limitations of each of them from the point of view of the intended concept were identified (e.g. their resistance to various types of interference effects). A possible combination of these methods in the direction of enhancing their white properties was proposed. Finally, the real and presumed applicability of white calibration methods in analytical practice is presented.