A rapid chromatographic
method for the determination of six phenolic acids (chlorogenic, ferulic,
gallic, p-coumaric, protocatechuic
and vanillic acids) by ultra performance liquid chromatography
(UPLC), was developed and applied for Brazilian tropical fruits mangaba
(Hancornia speciosa Gomes) and umbu (Spondias tuberosa Arruda Camara).
A multivariate statistical experimental design was employed to optimize
analytical conditions (solvent A, solvent B concentrations and flow rates).
Samples were cleaned-up by solid-phase extraction (SPE) with different solvents
(methanol and acetone) employing SPE cartridges (amine and octadecyl-silane).
The method using dihydrogen potassium phosphate 5 mmoL as solvent A and 8% acetonitrile
as solvent B presented limits of detection varying from 14 to 94 ng.mL, limits of quantification from 39 to 277 ng.mL-1 with 2 μL of injection volume while total run
time for all six compounds was only 9.6 minutes. Higher recovery was obtained
by extraction with methanol-acetone of 69.51% to 72.59% for protocatechuic acid and
69.58% to 126.31% for
the chlorogenic acid. The concentrations of chlorogenic, p-coumaric
and ferulic acids in mangaba extracts were 113.4, 32.1 and 1.5 μg.g-1, respectively while
concentrations of chlorogenic, protocatechuic, gallic, vanillic, ferulic and p-coumaric acids present in umbu fruit were 118.9, 141.3, 3.5, 2.5,
2.2 and 1.8 μg.g-1,
respectively.