In the search for a normalized procedure to replicate and compare single cell-inductively coupled plasma-mass spectrometry (SC-ICP-MS) experiments, SELM-1, a certified reference material containing selenium enriched yeast cells has been used. Selenium concentrations (both, intra- and extracellular) have been measured using either sequential or simultaneous procedures. Regarding quantitative results, the sequential procedure involving cell washing followed by freeze drying of the washed material and intracellular Se quantification using SC-ICP-MS provided best results. In this case, intracellular Se accounted for 1304 ± 48 mg kg⁻¹ (corresponding to 64% of the certified Se content). The average mass of Se per yeast cell was 41.6 fg Se with a dispersion of 1.6–279 fg Se/cell. In the isolated extracellular Se fraction, the Se concentration accounted for 412 ± 48 mg kg⁻¹ (about 21% of the total Se). Thus, the sequential procedure provided a total Se recovery of about 85% with respect to the certified value. The direct dilution and simultaneous measurement of intra- and extracellular Se by SC-ICP-MS provided results of 1024 ± 42 mg kg⁻¹ for intracellular and 316 ± 30 mg kg⁻¹ for extracellular Se representing a total recovery of about 66%. In both cases, an initial thorough characterization of the cell density per solid weighed material was conducted by flow cytometry and the cell integrity ensured using confocal microscopy. These results clearly demonstrated that with appropriate sample preparation, SC-ICP-MS is a unique tool, which is capable of providing quantitative information about intracellular and extracellular Se. In addition, SELM-1 seems the ideal tool to enable data normalization at the single cell level to replicate, benchmark, and improve new SC-ICP-MS studies by using the same material for data validation.

在寻找标准化程序来复制和比较单细胞电感耦合等离子体质谱 (SC-ICP-MS) 实验时，SELM-1 是一种经过认证的含有富硒酵母细胞的参考材料。硒浓度（包括细胞内和细胞外）已使用顺序或同步程序进行测量。关于定量结果，包括细胞洗涤、洗涤后材料冷冻干燥和使用 SC-ICP-MS 进行细胞内 Se 定量的顺序程序提供了最佳结果。在这种情况下，细胞内硒占 1304 ± 48 mg kg ^-1（对应于认证硒含量的 64%）。每个酵母细胞的平均 Se 质量为 41.6 fg Se，分散度为 1.6–279 fg Se/细胞。在分离的细胞外硒组分中，硒浓度为 412 ± 48 mg kg ^-1（约占总硒的 21%）。因此，顺序程序提供的总硒回收率约为认证值的 85%。通过 SC-ICP-MS 直接稀释和同时测量细胞内和细胞外的硒，细胞内硒为 1024 ± 42 mg kg ^-1，细胞内硒为 316 ± 30 mg kg ^-1细胞外硒的总回收率约为 66%。在这两种情况下，通过流式细胞术对每种固体称重材料的细胞密度进行初步彻底表征，并使用共聚焦显微镜确保细胞完整性。这些结果清楚地表明，通过适当的样品制备，SC-ICP-MS 是一种独特的工具，能够提供有关细胞内和细胞外硒的定量信息。此外，SELM-1 似乎是实现单细胞水平数据标准化的理想工具，可以通过使用相同的材​​料进行数据验证来复制、基准测试和改进新的 SC-ICP-MS 研究。