Since its introduction, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been applied in various fields ranging from earth to life sciences, offering fast acquisition of qualitative elemental data. [1] However, quantifying this data remains challenging due to the matrix dependent interaction between the laser and the sample. [2] General approaches require matrix matching the standard to the sample. Although certified reference materials offer reliable results, they are not available for all sample matrices, and in-house prepared standards suffer from limited homogeneity. Thus, it is of interest to further investigate into non-matrix matched quantification. Compared to other direct laser-based techniques, LA-ICP-MS offers the advantage of separating the ablation and ionization process, allowing ionization at constant conditions for all aerosols introduced into the ICP. While solution nebulization methods for quantifying laser-induced aerosols have been reported [3], using microdroplets as a liquid calibrant offers a promising alternative. Microdroplets dry on their way to the ICP and are expected to behave similarly to laser induced aerosols as these consist of nanoparticles and their agglomerates. [4]

This work presents a microdroplet approach for non-matrix matched quantification of laser induced aerosols. Quantification was performed on an ICP-TOFMS with a dual sample introduction setup for droplets and laser aerosols. Droplet behaviour compared to the laser aerosol was investigated and suitable internal standards were evaluated. Furthermore, the influence of matrix composition on analyte signal in droplets was studied. The addition of certain matrix elements at µg g^-1 levels, with analyte concentrations in the ng g^-1 range, affected sensitivity and isotope abundance patterns. Findings on droplet behaviour, matrix effects and respective figures of merit will be presented.

References

[1] T., Van Acker; S., Theiner; E., Bolea-Fernandez; F., Vanhaecke; G., Koellensperger Nature Reviews Methods Primers, 2023, 3, 1-18

[2] B. J., Fryer; S. E., Jackson; H. P. Longerich The Canadian Mineralogist, 1995, 33, 303-312

[3] E.V., Cromwell; P., Arrowsmith Analytical Chemistry, 1995, 67, 131-138

[4] B., Ramkorun-Schmidt; S.A., Pergantis; D., Esteban-Fernandez; N., Jakubwoski; D. Günther Analytical Chemistry, 2015, 87, 8687-8694