Retzmann A, Walls D, Miller K A, Irrgeher J, Prohaska T, Wieser M E
Department General, Analytical and Physical Chemistry, Chair of General and Analytical Chemistry, Montanuniversität Leoben, Leoben, Austria.
Department of Physics and Astronomy, University of Calgary, Calgary, Canada.
Anal Bioanal Chem. 2022 Jan;414(1):675-689. doi: 10.1007/s00216-021-03650-8. Epub 2021 Oct 15.
The application of Ca isotopic analysis in biomedical studies has great potential to identify changes in Ca metabolism and bone metabolism. Reliable measurement of Ca isotope-amount ratios is challenging considering limited Ca amounts and significant procedural blank levels. In this study, Ca purification was performed using the DGA Resin, optimized for low procedural blanks and separation of Ca from matrix elements and isobaric interferences (Na, Mg, K, Ti, Fe, Ba), while maintaining quasi-quantitative recoveries which are sufficient since a Ca-Ca double-spike (DS) was applied. Ca isotopic analysis was performed using multicollector thermal ionization mass spectrometry (MC TIMS). The obtained procedural Ca blank of ≤10 ng enables processing of limited Ca amounts down to 670 ng. Data reduction of the measured Ca isotope-amount ratios was performed using an in-house developed software solving the DS algorithm. Data quality was improved by extension of equilibration time of the sample-DS mixture and implementation of a normalization strategy for raw isotopic data. The reported δ(Ca/Ca) of NIST SRM 915a processed as a sample was found to be 0.01 ‰ ± 0.08 ‰ (2 SD, n = 15). Ca isotope-amount ratios of the reference material NIST SRM 1400 (bone ash), NIST SRM 1486 (bone meal), GBW07601 (human hair), and IAPSO (seawater) were in good agreement within uncertainty with literature data. Novel data on additional reference materials for biological tissues (hair) is presented, which might indicate a potential fractionation of Ca incorporated into hair tissue when compared to the blood pool.
钙同位素分析在生物医学研究中的应用对于识别钙代谢和骨代谢的变化具有巨大潜力。考虑到钙含量有限以及显著的程序空白水平，可靠测量钙同位素丰度比具有挑战性。在本研究中，使用DGA树脂进行钙纯化，该树脂针对低程序空白以及从基体元素和同量异位干扰物（钠、镁、钾、钛、铁、钡）中分离钙进行了优化，同时保持了准定量回收率，由于应用了钙-钙双稀释剂（DS），该回收率已足够。使用多接收热电离质谱仪（MC TIMS）进行钙同位素分析。获得的程序钙空白≤10 ng，能够处理低至670 ng的有限钙量。使用自行开发的求解DS算法的软件对测量的钙同位素丰度比进行数据处理。通过延长样品-DS混合物平衡时间以及对原始同位素数据实施归一化策略，提高了数据质量。作为样品处理的NIST SRM 915a的报告δ（Ca/Ca）为0.01‰±0.08‰（2SD，n = 15）。参考物质NIST SRM 1400（骨灰）、NIST SRM 1486（骨粉）、GBW07601（人发）和IAPSO（海水）的钙同位素丰度比在不确定度范围内与文献数据高度一致。本文还给出了生物组织（毛发）其他参考物质的新数据，与血池相比，这些数据可能表明纳入毛发组织中的钙存在潜在分馏。
