Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany.
Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstätter-Str. 11, 12489, Berlin, Germany.
Anal Bioanal Chem. 2022 Jan;414(1):251-256. doi: 10.1007/s00216-021-03636-6. Epub 2021 Sep 10.
The therapeutic dose of lithium (Li) compounds, which are widely used for the treatment of psychiatric and hematologic disorders, is close to its toxic level; therefore, drug monitoring protocols are mandatory. Herein, we propose a fast, simple, and low-cost analytical procedure for the traceable determination of Li concentration in human serum, based on the monitoring of the Li isotope dilution through the partially resolved isotope shift in its electronic transition around 670.80 nm using a commercially available high-resolution continuum source graphite furnace atomic absorption spectrometer. With this technique, serum samples only require acidic digestion before analysis. The procedure requires three measurements-an enriched Li spike, a mixture of a certified standard solution and spike, and a mixture of the sample and spike with a nominal Li/Li ratio of 0.82. Lanthanum has been used as an internal spectral standard for wavelength correction. The spectra are described as the linear superposition of the contributions of the respective isotopes, each consisting of a spin-orbit doublet, which can be expressed as Gaussian components with constant spectral position and width and different relative intensity, reflecting the isotope ratio in the sample. Both the spectral constants and the correlation between isotope ratio and relative band intensity have been experimentally obtained using commercially available materials enriched with Li isotopes. The Li characteristic mass (m) obtained corresponds to 0.6 pg. The procedure has been validated using five human serum certified reference materials. The results are metrologically comparable and compatible to the certified values. The measurement uncertainties are comparable to those obtained by the more complex and expensive technique, isotope dilution mass spectrometry.
锂（Li）化合物的治疗剂量接近其毒性水平，因此广泛用于治疗精神和血液疾病；因此，必须进行药物监测。在此，我们提出了一种快速、简单且低成本的分析程序，用于痕量测定人血清中的 Li 浓度，该程序基于通过在约 670.80nm 的电子跃迁中部分分辨同位素位移来监测 Li 同位素稀释，使用市售的高分辨率连续光源石墨炉原子吸收光谱仪。使用这种技术，血清样品在分析前仅需要酸性消化。该程序需要进行三次测量 - 富含 Li 的加标物、标准溶液和加标物的混合物以及具有标称 Li/Li 比为 0.82 的样品和加标物的混合物。镧已被用作波长校正的内标光谱。光谱被描述为由各自同位素的贡献的线性叠加，每个同位素都由自旋轨道偶合组成，自旋轨道偶合可以表示为具有恒定光谱位置和宽度以及不同相对强度的高斯分量，反映了样品中的同位素比值。光谱常数和同位素比值与相对带强度之间的相关性都是使用商业上可获得的富含 Li 同位素的材料通过实验获得的。获得的 Li 特征质量 (m) 对应于 0.6pg。该程序已使用五种人血清认证参考材料进行了验证。结果在计量学上可比较且与认证值兼容。测量不确定度与更复杂和昂贵的技术 - 同位素稀释质谱法相当。
