Fig. 3

Chromatogram of standards and collected fractions associated to the standards retention times during gradient HPLC. a Standard 2 molecule (200 μg ml⁻¹). b Standard 1 molecule (400 μg ml⁻¹). c The zoomed fraction areas of one HPLC run related to extracted supernatant. Collection of the samples was performed from two fractions (presented in green time windows). First fraction was collected between 11.90 min and 12.90 min to cover the specific retention time of standard 2 (12.6 min). Second fraction was collected between 14.40 and 15.40 min according to the retention time of standard 1 (14.8 min). The red arrows presented in image b (S1 and S2) point at the interested peaks in the fractioning time which are representing the retention time of standard 1 and standard 2