Determination of Scandium (Sc), Yttrium (Y), and Rare-Earth Elements (REEs) in Mafic and Ultramafic Rock Powder by a Modified and Validated Digestion Protocol and Inductively Coupled Plasma – Mass Spectrometry (ICP-MS)

The global demand for rare earth elements (REEs) has been associated with the increased use of renewable energy technologies. However, due to the low occurrence of REEs in economic sources, such as geologic samples, it is essential to employ suitable sample preparation methods and measurement techniques that allow for reliable quantification. While acid digestion procedures have been conventionally used to free metals from silicate rocks, few studies have evaluated these methods for quantitative measurement of REEs, including Sc and Y in mafic-ultramafic rocks. This study involves validating a modified digestion procedure to facilitate the determination of Sc, Y, and REEs in mafic-ultramafic matrices. Three reference materials (RMs) (OKUM, BHVO-1, and JB-1a) were used to assess the performance of this modified method. The calculated percent error (< 10%) for most elements was in good agreement with the reference values, except La in OKUM, Er in BHVO-I, and Eu, Gd, Tb, Ho, and Er in JB-1a. The precision of the modified method was satisfactory, with values generally below 5%. The smooth chondrite normalized REE patterns indicate good quality data. The t-values of the studied elements were lower than the t-critical value (± 12.71), suggesting no significant differences between the analytical and Intertek values. Thus, the modified method could be used as a viable alternative in determining REEs in Ni laterite samples by ICP-MS. (author)