HPLC/ELS is widely used and its principle is well described [26].Non-linearity is a feature of the ELS detector; thus, nonlinearcurves have been described for several compounds when analyzed using ELS detectors [27]. Nevertheless, the lack of linearity did not exclude the use of ELS detection for LA quantification in skin,considering that the non-linear curves include a linear interval.Another characteristic is that the detector response depends on the mass of the analyte; therefore, it is necessary to prepare individual curves for each substance