蛋白质标准物质的可用性以及其表征、定量和纯度评估的方法，目前是绝对定量蛋白质组学中的瓶颈。在本研究中，我们介绍了一种基于ICP-MS硫检测的绝对定量分析策略，使用硫酸盐作为通用标准来定量和证明蛋白质标准物质的质量纯度。该方法将毛细管色谱分离与ICP-MS和ESI-MS的平行检测相结合，分别确定蛋白质形态的浓度和身份。该方法的可行性已使用重组人细胞因子标准物IP-10和Flt3L（2批次）进行了证明，这些标准物质是癌症或炎症性疾病的相关生物标记物。每个关键因素（传输效率、柱回收、信号稳定性和内部标准适用性）均纳入考虑，并使用认证BSA标准物质作为质量控制进行验证。IP-10和一批次Flt3L的蛋白质定量值和相应的质量纯度认证非常高（分别为100％和86％）。另一批次Flt3L的较低质量纯度（<70％）与ESI-MS的平行观察结果一致，显示出显著的氧化过程产生的蛋白质形态。 版权所有©2023 Elsevier B.V.。

The availability of protein standards and methods for their characterization, quantification, and purity assessment are currently a bottleneck in absolute quantitative proteomics. In this work, we introduce an absolute quantitative analytical strategy based on ICP-MS sulfur detection that uses sulfate as generic standard to quantify and certify the mass purity of protein standards. The methodology combines capillary chromatographic separation with parallel detection with ICP-MS and ESI-MS to determine proteoforms concentration and identity, respectively. The workability of the methodology was demonstrated using recombinant human cytokine standards IP-10 and Flt3L (2 batches), which are relevant biomarkers for carcinoma or inflammatory diseases. Every key factor (transport efficiency, column recovery, signal stability and internal standard suitability) was taken into account and certified BSA standard was used as quality control for validation purposes. Protein quantification values and resulting mass purity certification of IP-10 and one batch of Flt3L were very high (100 and 86%, respectively). Lower mass purity obtained for another batch of Flt3L (<70%) concurred with the finding of significant proteoforms resulted from oxidation processes as observed by parallel ESI-MS.Copyright © 2023 Elsevier B.V. All rights reserved.