Utilization of fluorescein sodium salt for the indirect fluorimetric detection in micellar electrokinetic chromatography

The potential of fluorescein sodium salt to generate a background signal in indirect fluorimetric detection in micellar electrokinetic chromatography (MEKC) has been studied by using a sample test containing various alcohols (methanol, ethanol, propan-1-ol, propan-2-ol, 2-methylpropan-1-ol, pentan-3-ol, 2-methylbutan-1-ol, 3-methylbutan-1-ol), acetaldehyde, acetone and ethyl acetate. In order to optimize sample test resolution and detection sensitivity, we have studied different parameters: sodium dodecyl sulfate concentration, electrolyte ionic strength, applied voltage as well as that of the addition of an organic cosolvent within the running electrolyte. Although the micellar pseudo-phase was not able to be saturated with the fluorophore in order to obtain the maximal detection sensitivity, the detection thresholds were satisfactory. By way of example, the detection threshold reached for 3-methylbutan-1-ol is 0.03% (v/v). The quantitative aspect was approached with ethanol titration in a commercial white wine. Finally the repeatability relating to, on the one hand, the effective electrophoretic mobilities and, on the other hand, the corrected areas has also been studied.