Development of validation methods to determine cadmium in cocoa almond from the beans by ICP-MS and ICP-OES

Abstract

There are many publications on the quantification of cadmium (Cd) in cocoa beans and cocoa products. However, quantifying Cd in cocoa almonds from beans involves a critical step in the sample preparation process, such as dehulling the beans. This process is essential since it can affect the quality of the results if it is not carried out correctly because it has been reported that the testa presents cadmium concentrations between 3 and 4 times compared to almond. Therefore, this is the first study to validate two analytical methods for reliable Cd quantification in cocoa beans using inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) after microwave-assisted digestion that shows the proper pretreatment of cocoa beans to obtain accurate results from the analyzed samples. The Cd quantification limits using ICP-MS and ICP-OES were 0.005 mg kg−1 and 0.043 mg kg−1, respectively. The Cd recovery percentages with certified reference material (baking chocolate NIST® SRM® 2384) for ICP-MS and ICP-OES were 95% and 92%, respectively. The combined standard uncertainties obtained to determine Cd utilizing ICP-MS and ICP-OES did not exceed 8%. The laboratory's sample analysis of internal reference materials (IRM 1 and IRM 5) allowed quantifying Cd with values ​​lower and higher than the minimum amount allowed by the European regulation for cocoa-derived products (0.1 mg kg−1 of Cd).