Bioimaging is widely used to visualize the presence or absence of certain tissues, cells, and low-molecular-weight compounds. Metallomics studies have revealed important roles of metals in cells and bodies, providing crucial information to understand the accumulation or deficiency of those metals. Laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) can provide localization information of the accumulation of elements on solid samples. Consequently, bioimaging techniques using LA-ICP-MS have been developed to investigate the distribution of metals in biological tissues. [1]

The quantitation of metals in solid samples using LA-ICP-MS involves several methodologies: (1) signal calibration using inorganic matrix-based standards, (2) signal calibration using element-spiked tissue samples, and (3) normalization to bulk metal components as 100%. For the first method, commercially available glass- and metal-based solid reference materials are unsuitable due to discrepancies in ablation efficiency and matrix effects of the sample aerosol when compared to carbon-based biological tissue samples. The second method requires advanced skills, and the sample preparation stage is time-consuming. The challenge of the third method is scanning all elements within a single ablated spot using quadrupole-based ICP-MS systems. Recently, an organic matrix-based standard has gained attention as a promising solution to the issues associated with the first and second methods. In this study, we used LA-ICP-MS to measure the organic matrix-based standard and element-spiked tissue sections, developing a method to quantitatively evaluate the localization of metals in biological tissues.

The instrumentation included an 8900 Triple Quadrupole ICP-MS (Agilent Technologies) equipped with an ESL 213 Laser Ablation System (Elemental Scientific Inc). Due to the supply shortage of helium (He) in many countries, argon was used as the carrier gas from the LA system to the ICP-MS gas instead of He gas. Based on the operating conditions developed in a previous study that achieved a low detection limit for phosphorus, the MS/MS configuration of the triple quadrupole ICP-MS was operated in oxygen mass-shift mode. Control of the LA-ICP-MS was automated using ICP-MS MassHunter software (Agilent).

For Research Use Only. Not For Use In Diagnostic Procedures.

References

[1] M. Iwase, Y. Tanaka, N. Suzuki, Y. Ogra, J. Toxicol. Sci. Vol.46, No.5, 193-198, 2021