Validação de método cromatográfico para a quantificação de ácidos anacárdicos em pedúnculo de caju

Abstract

The cashew apple has high nutritional value, having a wide variety of phenolic compounds in its composition. Among these compounds, anacardic acids (AcAn) have biological activity and high commercial value, but influence the taste and consequently the acceptance of cashew apple. Despite the AcAn quantification methodologies described in the literature, the small amounts of AcAn present in the cashew apple require a sensitive method of quantification. Given this, the objective of this work was to validate a chromatographic methodology of quantification of anacardic acids in cashew apples. Samples containing AcAn were analyzed on a high-performance liquid chromatograph coupled to a diode array detector, equipped with a reversed phase C18 (150 × 4.6 mm × 5 μm) column using acetonitrile and water as the mobile phase both acidified with acetic acid in an isocratic mode (80:20:1). Eight different concentrations (varying from 1 to 100 µg.mL-1) of the external standart AcAn 15:3 obtained by preparative chromatography (Purity = 99.04%) were used. The calibration curve obtained presented satisfactory precision values for intra-day (CV = 0.20%) and inter-day (CV = 0.29%); linearity (y = 2333.5x + 2956.2; r2 = 0.9979); repeatability with respect to retention time (CV = 0.45%) and areas (CV = 0.30%); selectivity and detection limits (0.25 µg.mL-1) and quantification (1.0 µg.mL-1). For the determination of the amount of anacardic acids in real samples, we used the methanol extract of cashew pulp, which presented an average recovery value of approximately 90% of total anacardic acids in two successive extractions. The total anacardic acid contents were 0,45 mg. 100g-1, 0,74 mg. 100g-1, 1,11 mg. 100g-1, 1,24 mg. 100g-1, 1,24 mg. 100g-1 in cashew apple samples from five cashew clones.