Multielement determination of metals in edible seeds by HR-CS GF AAS and direct analysis

Abstract

This work reports, for the first time, the multielement determination of Cd, Ni and Fe concentrations in edible seeds via high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS), using direct solid sample analysis. First, Cd (228.802 nm) concentration was determined using 400 and 1600 °C as pyrolysis and atomisation temperatures, respectively. In sequence, from the same sample aliquot, Ni (232.003 nm) and Fe (232.036 nm) concentrations were determined using 2500 °C as the atomisation temperature. A combination of Pd/Mg and H2O2 was used as a chemical modifier to improve the precision and overcome smoke interferences. Multielement aqueous standard solutions were used for calibration, and the detection limits were 3.1 µg kg−1 for Cd, 0.062 mg kg−1 for Ni and 3.4 mg kg−1 for Fe. The trueness was proven by analysing a standard reference material of Tomato Leaves (NIST SRM 1573a). The following concentration ranges were found in the samples: 39–254 µg kg−1 for Cd; 1.1–8.0 mg kg−1 for Ni; and 38–147 mg kg−1 for Fe. The Cd contents in with-shell pumpkin and in roasted and raw sunflower seed samples were above the maximum acceptable Cd level in cereals, as established by the Codex Alimentarius Commission of 100 µg kg−1.