Development and comparison of two validated methods to determine cadmium and arsenic in Colombian rice by ICP-MS and ICP-OES

Abstract

Some metals are essential for the diet, such as iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn). However, there are heavy metals that are not biodegradable, so they are not essential for metabolism since they do not fulfill a physiological role in humans or plants. Therefore, they become an adverse factor in terms of health due to their cumulative capacities, such as cadmium (Cd), chromium (Cr), lead (Pb), arsenic (As), and mercury (Hg). This study aimed to develop and compare two methods to determine the content of Cd and As in rice grains (Oryza sativa L.). The samples were subjected to microwave-assisted acid digestion with HNO3, and H2O2 [2:1] as this method is useful to prepare samples with the presence of organic matter since it minimizes the loss of analytes and sample contamination. Subsequently, these were analyzed by quadrupole inductively coupled plasma-mass spectrometry (ICP-MS) equipped with a collision/reaction cell and by inductively coupled plasma-optical emission spectrometry (ICP-OES). The performance of the proposed method was evaluated under selectivity, sensitivity, linear range, limits of detection and quantification, precision, intermediate precision, and reproducibility parameters. The results showed that the digestion method was satisfactory for sample preparation and the ICP-MS technique obtained lower quantification limits compared to ICP-OES. However, due to the quantified concentrations, the results indicated that both methods are suitable to determine Cd and As in rice, considering the maximum limits allowed in different types of rice regulated in the Codex Alimentarius and the European Union.

Keywords

• Heavy metals
• Validation
• Microwave-assisted acid digestion
• Quantification limits
• Food