Sequential and simultaneous determination of chlorine, iron, and silicon in beer samples by high-resolution continuum source graphite furnace molecular and atomic absorption spectrometry

Abstract

An analytical method was proposed for the determination of Cl (via the InCl molecule at 267.2181 nm), Fe (252.7435 nm), and Si (252.8508 nm) in beer samples using sequential and simultaneous determination by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) in combination with high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS). First, Cl was determined using 600 °C and 1800 °C as the pyrolysis and vaporization temperatures, respectively, using In as a forming agent of the InCl molecule. Then, Si and Fe were simultaneously determined from the same sample aliquot using 2600 °C as the atomization temperature. A solution of Pd/Mg was used as a chemical modifier. The matrix effect was evaluated, and the results indicated that external calibration was possible using aqueous standard solutions. The limit of detection and quantification were 0.05 and 0.17 mg L–1 for Cl, 0.08 and 0.26 mg L–1 for Si, and 2.0 and 6.7 μg L–1 for Fe, respectively. Recovery tests presented interval between 85 and 120% for the three analytes. Accuracy was confirmed by comparing the results obtained by the proposed method with those obtained by inductively coupled plasma optical emission spectrometry for Si and Fe and by ion chromatography for Cl. The concentration range found in ten beer samples was 106–277 mg L–1 for Cl, 15–37 mg L–1 for Si, and < 20–73 μg L–1 for Fe.