Comparison of background corrected fluorescence correlation spectroscopy and fluorescence lifetime correlation spectroscopy: dilution series revisited

We performed quantitative tests in order to compare the practical limits of FCS and FLCS. Unlike conventional FCS, FLCS yields precise and correct concentration values from as low as picomolar to micromolar concentrations. We discuss some of the inherent technical limitations of FCS and demonstrate that they are easily overcome by FLCS employing the simplest confocal detection scheme.