Determination of free Mg2 + in turbid samples with the coexistence of interfering Ca2 + using extended quantitative fluorescence model

Abstract

Ratiometric fluorescence indicators are among the most popular fluorescence indicators due to their robustness to variations in probe loading, bleaching, optical path length, illumination intensity, etc. However, the presence of interfering ions, scatterers, and absorbers in the samples under study can render the traditional ratiometric model invalid. In this contribution, the quantitative fluorescence model (QFM) was further developed and extended for the quantification of free Mg2+ in turbid samples with the coexistence of interfering Ca2+ using ratiometric fluorescence indicator 2-(4-Amino-3-hydroxyphenyl) indole-6-carboxylic acid N′,N′,O′-triacetic acid Indo 1 analog (Mag-Indo-1). Experimental results showed that the concentrations of free Mg2+ in turbid media can be determined by the extended QFM model with an average relative predictive error value of about 6.0%, comparable to the results obtained by atomic absorption spectrometry. The results achieved in this contribution fully demonstrated that the application of advanced calibration model could realize accurate quantification of the ion of interest in the presence of interfering ions in turbid media using a ratiometric fluorescent indicator without a pronounced selectivity for the ion of interest.