Determination of lithium in human serum by isotope dilution atomic absorption spectrometry.

Content Provider	Europe PMC
Author	Winckelmann, Alexander Morcillo, Dalia Richter, Silke Recknagel, Sebastian Riedel, Jens Vogl, Jochen Panne, Ulrich Abad, Carlos
Abstract	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 6Li spike, a mixture of a certified standard solution and spike, and a mixture of the sample and spike with a nominal 7Li/6Li 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 (mc) 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.Graphical abstractSupplementary InformationThe online version contains supplementary material available at 10.1007/s00216-021-03636-6.
ISSN	16182642
Journal	Analytical and Bioanalytical Chemistry
Volume Number	414
PubMed Central reference number	PMC8748318
Issue Number	1
PubMed reference number	34505166
e-ISSN	16182650
DOI	10.1007/s00216-021-03636-6
Language	English
Publisher	Springer Berlin Heidelberg
Publisher Date	2021-09-10
Publisher Place	Berlin/Heidelberg
Access Restriction	Open
Rights License	Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. © The Author(s) 2021
Subject Keyword	Lithium Human serum Isotope dilution Atomic absorption spectrometry High-resolution continuum source graphite furnace atomic absorption spectrometry
Content Type	Text
Resource Type	Article
Subject	Analytical Chemistry Biochemistry