Investigation of chemical modifiers for the determination of cadmium and chromium in fish oil and lipoid matrices using HR-CS GF AAS and a simple 'dilute-and-shoot' approach

This work presents simple and reliable methods for the determination of Cd and Cr in fish oil and lipoid samples by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). Only a simple dilution using 1-propanol was adopted as sample preparation for the determination of Cd and Cr in order to reduce the high viscosity of the lipoid samples. Pt was employed as permanent chemical modifier and Pd was used as chemical modifier in solution, added over the sample for the determination of Cd for a better performance and sensitivity. Cr was determined without a chemical modifier. The accuracy of the proposed methods was evaluated by comparison with microwave-assisted digested samples and determination by HR-CS GF AAS, showing good agreement between 2% and 13% for both elements without statistical difference (confidence interval of 95%). The limits of detection for Cd and Cr were 0.5 pg and 7 pg, respectively, corresponding to 0.15 ng g− 1 and 2 ng g− 1, respectively. The developed methods can be described as clean, fast and accurate, which did not require any sample pre-treatment stages, such as digestion or matrix oxidation, and could be extended to different lipoid matrices, demonstrating their robustness.