Calibration strategies for laser ablation ICP-MS in biological studies: A review

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has attracted attentions for its high sensitivity and sufficient spatial resolution in the in-situ analysis and imaging in biological studies. However, due to the matrix effect and elemental fractionation, achieving quantitative analysis of elements or proteins in biological samples are still challenging. Calibration is a necessary step for quantification and can compensate the deviation and realize accurate quantitative measurement by LA-ICP-MS. In this review, we discussed several calibration strategies for quantitative analysis of LA-ICP-MS in biological studies, which includes internal standardization, external calibration with commercially certified reference materials (CRMs), in-house standards or online addition calibration, and isotope dilution quantification strategies. Furthermore, calibration based on machine learning is also proposed as a potential quantitative strategy by LA-ICP-MS. This work will promote the introduction of calibration strategies of LA-ICP-MS, which will be helpful to achieve accurate quantitative results by this in-situ analysis technique.