Estudo quantitativo comparativo de ácido ascórbico em tomates convencionais e orgânicos por cromatografia líquida de alta eficiência

Abstract

The tomato is a fruit originally from Central and South America, and has been cultivated since the 16th century, it is currently one of the most produced and consumed fruit worldwide. Tomato plantation differs in tutored low and is directed, respectively, for fresh consumption and the industry. Tomatoes consumed in natura, directly on the table of Brazilians, can have organic or conventional cultivation. The main characteristic of conventional cultivation is the use of pesticides and the organic one is carried out without this type of input. It is a fruit that has a high nutritional value, as it is rich in minerals, vitamins, amino acids, and fibers. Vitamin C (ascorbic acid) is an important compound contained in tomatoes; however, it is easily oxidized because of its hydroxyl groups. The objective of this work was to carry out a comparative study of the amount of ascorbic acid in organic and traditional tomatoes. To quantify ascorbic acid (AA) in tomato samples, High-Performance Liquid Chromatography (HPLC) was used with a Solid Phase Extraction (SFE) sample preparation. Quantification was conducted on HPLC-DAD using an ACE 3 C18 reversed-phase chromatography column (15 cm x 2.1 mm). The mobile phase used was a 0.2 mol.L-1 solution of monobasic potassium phosphate (KH2PO4) acidified with phosphoric acid to pH 2.4. The method conditions were an isocratic elution, with a flow rate of 0.5 mL/min, at room temperature, and an injection volume of 20 µL. The analysis was performed at a wavelength of 254 nm and the peak integration was obtained using Shimadizu's LCsolution® software. The concentrations obtained after the analysis showed a significant difference in the amount of ascorbic acid between the tomato samples, which may be related to the storage time for each type of tomato. It is concluded that the technique applied to quantify AA is valid and can be applied in future works.