A method may comprise: exposing a substituted chromone dissolved in a solvent to a sample; taking a fluorescence measurement of the sample after exposure to the substituted chromone; and determining a presence or absence of one or more ions in the sample, a concentration of the one or more ions in the sample, or both based on the fluorescence measurement.

A method may comprise: exposing a substituted chromone dissolved in a solvent to a sample; taking a fluorescence measurement of the sample after exposure to the substituted chromone; and determining a presence or absence of one or more ions in the sample, a concentration of the one or more ions in the sample, or both based on the fluorescence measurement.