Validación de un método analítico para la determinación de arsénico total en muestras de suelo por espectrofotometría de absorción atómica con generación de hidruros

Abstract

In Paraguay, research on arsenic contamination is still incipient. This study aimed to validate the analytical method for the determination of total arsenic in soil samples by atomic absorption spectrophotometry with a hydride generation (HG - AAS). For its validation, a blank sample was collected from an area of null anthropogenic activity and, for its application, ten samples from the Tebicuary River basin. The samples were dried, sieved, homogenized, and digested by a microwave oven. The quantification was performed by HG - AAS. Analytical performance parameters such as selectivity, linearity, sensitivity, accuracy, LOD, LOQ, robustness, uncertainty, and applicability were evaluated. The method was selective for As and met the acceptance criteria. Linearity from 0.2 to 12 µg·L-1 (r > 0.99), sensitivity (m = 0.0395 ± 0.005), accuracy (%R > 95 %), repeatability (CV = 4.26 %), reproducibility (CV = 4.52 %), LOD (0.11 mg·kg-1) and LOQ (0.21 mg·kg-1). The method was robust to variations in pH and particle size. From the ten samples analyzed, one had a total As concentration higher than 20 mg·kg-1.