Considering the ionic strength for proper use of 1 or 2-ligands model for static fluorescence quenching or enhancement.

We formally describe a 1- or 2-ligands fluorescence quenching or exhaustion model that takes ionic strength into account. We give ready-to-use formulas, which are easy to implement on a common spreadsheet, to determine complexing capacities and apparent stability constants of fluorescence ligands by adjusting quenching or enhancing experimental curves. The strength of our model is to consider parameters that have rarely taken in account in the literature, resulting in a significant improvement in the quality of the modeling: the charge associated with one or two ligands, and ionic strength. The model predicted fluorescence at various ionic strengths from parameters determined at a given ionic strength. This model is suitable for many applications, such as complexation of dissolved natural organic matter with metal ions, even in sea water, or biologic media.

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