HPLC-DAD Validation Method for Quantifying Gallic Acid in the Aerial Parts of Schinus terebinthifolius

Schinus terebinthifolius Raddi (Anacardiaceae), commonly known as "pimenta rosa", "aroeira da praia", "aroeira", "aroeirinha", and "cabu & iacute;" is frequently used in traditional medicine to address various conditions, including skin wounds, ulcers, tumors, diarrhea, arthritis, as well as urinary and respiratory tract infections. This study aimed to develop and validate an analytical method using high-performance liquid chromatography with diode array detector (HPLC-DAD) for quantifying gallic acid (GA) in methanolic extracts of S. terebinthifolius leaves, branches, and fruits. The chromatographic separations utilized a reversed-phase Zorbax Eclipse XDB-C18 column with an isocratic elution mode of acetonitrile/methanol/water acidified with 0.2% formic acid. The flow rate was 0.8 mL min-1, and detection occurred at 254 nm. The developed HPLC-DAD method demonstrated selectivity, with a GA retention time of 5.263 min and absorption maxima at 220 and 271 nm. The method exhibited high linearity (coefficient of 0.9996), precision (relative standard deviation (RSD) values < 5%), and robustness. Accuracy ranged from 100.28 to 111.71%, with an average recovery of 105.41% and an average RSD of 3.46%. These validated results play a crucial role in assessing and standardizing raw materials containing S. terebinthifolius, emphasizing the reliability of the developed HPLC-DAD method for GA quantification in different plant parts.