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

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 abstract

High-resolution continuum source graphite furnace molecular absorption spectrometry for the monitoring of Sr isotopes via SrF formation: a case study

“…However, they are expected to be minimal, so the use of high-resolution spectrometers is oen necessary. Even then, the energy differences observed for atomic transitions of different isotopes are normally so small that the number of practical applications based on atomic spectrometry is limited to isotope ratios of light atoms, such as boron 13 or lithium, 14,15 or else to those of heavy ones that show a difference of various mass units. 16,17 Alternatively, the use of molecular spectra opens new possibilities in this eld, as demonstrated via LAMIS.…”

Multielement analysis in soils using nitrogen microwave inductively coupled atmospheric-pressure plasma mass spectrometry

“…Both methods provided comparable results, which lie mostly within the reference ranges. The metrological compatibility of the obtained results with the reference values was validated using the En value (Tables S3-S6), which equals the difference between the two values divided by the expanded uncertainty of this difference 34,35 . When En is less than 1, the values are considered metrologically compatible.…”

“…The metrological compatibility of the obtained results with the reference values was validated using the E n value (Tables S3-S6 †), which equals the difference between the two values divided by the expanded uncertainty of this difference. 34,35 When E n is less than 1, the values are considered metrologically compatible. The results of the RV samples are metrologically compatible with the reference values, whereas several values obtained for the BRM samples are not metrologically compatible due to the small reference ranges.…”

A spin–orbit configuration interaction study of the low-lying electronic states of the diatomic lithium antimonide cation

“…Lithium-ion batteries have been widely used in energy storage devices, which are currently one of the most promising technologies [20][21][22][23][24][25][26][27][28][29][30]. Lithium has also been utilized in special glasses and ceramics [31][32][33][34][35], as well as in wearable sensors [36][37][38] and pharmacology [39][40][41]. Our current knowledge of lithium and its compounds can be found in reviews [42][43][44][45][46][47][48][49][50][51] and the references therein.…”