Liquid chromatography is currently the analytical method of choice for GAs.20 The major problem with HPLC techniques is
the inadequate resolution of GAs differing by carbon number and unsaturation, such as C13:0 and C15:1 or C15:0 and
C17:1, as well as the inability to resolve double bond positional isomers. Lee et al.21 used column switching (heart cutting) to minimize matrix effects and improve resolution. The method was validated, and the LOD and LOQ for the C15:1 and C17:1 GAs were 10 and 40 ppb with a diode array detector. Negative mode ESI/MS/MS was used for identification of the GAs. Udrescu et al.22,23 developed an RPLC/UV method that avoided the time-consuming solvent evaporation step involved in most HPLC analysis methods for GAs. The method involved an acidified methanol/water extraction followed by LLE with hexane (20:1) for one standardized extract of G. biloba. A large volume (50 μL) of the hexane was injected into the RPLC column with a very steep gradient. The method was validated,and the LOQ for GAs was 1 ppm. Again, the GAs were confirmed by MS2 methods, and collision-induced fragmentation schemes were presented. Gawron-Gzella et al.24 used HPLC to analyze several pharmaceuticals and dietary supplements
for GAs. The total concentrations of GAs ranged from 2 to 8000 ppm.
Liquid chromatography is currently the analytical method of choice for GAs.20 The major problem with HPLC techniques isthe inadequate resolution of GAs differing by carbon number and unsaturation, such as C13:0 and C15:1 or C15:0 andC17:1, as well as the inability to resolve double bond positional isomers. Lee et al.21 used column switching (heart cutting) to minimize matrix effects and improve resolution. The method was validated, and the LOD and LOQ for the C15:1 and C17:1 GAs were 10 and 40 ppb with a diode array detector. Negative mode ESI/MS/MS was used for identification of the GAs. Udrescu et al.22,23 developed an RPLC/UV method that avoided the time-consuming solvent evaporation step involved in most HPLC analysis methods for GAs. The method involved an acidified methanol/water extraction followed by LLE with hexane (20:1) for one standardized extract of G. biloba. A large volume (50 μL) of the hexane was injected into the RPLC column with a very steep gradient. The method was validated,and the LOQ for GAs was 1 ppm. Again, the GAs were confirmed by MS2 methods, and collision-induced fragmentation schemes were presented. Gawron-Gzella et al.24 used HPLC to analyze several pharmaceuticals and dietary supplementsfor GAs. The total concentrations of GAs ranged from 2 to 8000 ppm.
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