Separation and identification of a complex flurbiprofen-polyethylene glycol mono- and diester mixture via a hyphenated HPLC-DAD-HRMS/SPE NMR system.

We report the use of a hyphenated HPLC-DAD(diode array detector)-HRMS/SPE NMR system for the separation and isolation of a complex mixture of esters, containing substances with very similar LC retention times. The literature known mono- and diesters of the drug Flurbiprofen and polyethylene glycol, which form a large number of substances with varying chain lengths, were chosen for this study. We demonstrate the use of this hyphenated system to quickly and effectively isolate sixteen of these highly similar individual esters in an automated fashion, demonstrating its applicability in standard pharmaceutical analysis and quality control of drugs. Both, synthetic solutions of these esters and extracts from Flurbiprofen lozenges were used for this purpose. By the sole use of this system, the individual compounds were isolated and UV, HRMS and 1D and 2D NMR data could be collected, enabling the identification and differentiation of the individual esters.