Determination of Quercetin, Gallic Acid, Resveratrol, Catechin and Malvidin in Brazilian Wines Elaborated in the Vale do So Francisco Using Liquid-Liquid Extraction Assisted by Ultrasound and GC-MS

In this work, a fast and simple methodology has been applied for the determination of gallic acid, resveratrol, catechin and malvidin in Brazilian wines by gas chromatography-mass spectrometry. The procedure included a stage of ultrasound-assisted liquid-liquid extraction and subsequent derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and GC-MS analysis. The limit of detection varied from 0.41 to 1.18 mg L-1 in all the analytes. The relative standard deviations calculated for 8.0 and 20 mg L-1 were 1.90 and 0.82 % for gallic acid, 3.08 and 1.22 % for catechin, 1.30 and 0.44 % for malvidin, 1.50 and 0.53 % for resveratrol, and 1.41 and 0.61 % for quercetin. The developed methodology was applied for the analysis of red wine samples collected in the So Francisco region, Bahia state, Brazil. Quercetin concentration varied from 2.4 to 3.0 mg L-1, gallic acid 21.4-56.3 mg L-1, resveratrol 1.5-5.9 mg L-1, malvidin 15.3-32.2 mg L-1, and catechin 11.71-18.2 mg L-1. The obtained concentrations are in agreement with those reported in the literature.