A novel extraction-based procedure for the determination of cadmium in marine macro-algae using HR-CS GF AAS

Abstract

This work proposes a simple method for the determination of Cd in macro-algae by high-resolution continuum source graphite furnace atomic absorption spectrometry. An acid digestion procedure in a thermostatic bath has been developed using only small volumes of HNO₃ and H₂O₂. The acid and oxidant concentrations as well as the bath time have been optimized using multivariate analysis, aiming at a total extraction of the analyte without spending much time with sample preparation. Ir has been employed as the permanent chemical modifier for improving performance and sensitivity. The accuracy of the proposed method has been evaluated by comparison with inductively coupled plasma mass spectrometry after microwave-assisted acid digestion, showing results without statistical difference (based on a t-test with a confidence interval of 95%). The results were also compared with a certified reference material, BCR 679 (white cabbage), and the value obtained with the proposed method did not show any statistical difference with the certified one. The limit of detection of the method was 7.5 ng g⁻¹ Cd. The proposed procedure can be described as safe, reliable, fast, accurate and low-cost, mainly when compared with microwave-assisted digestion, which demands a relatively large volume of acids, specific instrumentation and significantly more time.