Abstract <p>For elemental analysis of candidate reference materials for the composition of black shales (SLg-1A and SChS-1A), we used inductively coupled plasma mass spectrometry (ICP-MS) after fusion of samples with lithium metaborate and microwave acid digestion without prefiring. The use of the proposed sample preparation techniques, which offer high speed and ease of implementation, enabled ICP-MS determination of a wide range of elements in each material, including Cd, Mo, Sb, Sn, Te, W, Tl, and Bi, for which data were missing or whose concentrations were evaluated only approximately in SLg-1 and SChS-1 certification. The percentages of analytes were determined in a single measurement cycle on an Element magnetic sector mass spectrometer with low, medium, and high resolution, using external calibration against solutions having a similar matrix composition, in combination with an internal standard in order to reduce the matrix effect and monitor the signal drift. For most elements, the relative standard deviation in ICP-MS analysis is under 10% after fusion and 6 to 20% after acid digestion. We have demonstrated experimentally that, in ICP-MS determinations of Ag and Au in samples, the sample weight should be increased to 1 g to ensure that the sample is representative.</p>