[Analytical Chemistry] The chemical characterization of scarce or heterogeneous solid samples remains a significant analytical challenge due to the high material quantities required by conventional techniques.

Here, a microsampling approach is presented that combines laser ablation, optical trapping, and single-particle laser-induced breakdown spectroscopy (μLA-OT-SP-LIBS) for the analysis of discrete microdomains with minimal sample consumption.

In this scheme, particles were in situ generated by laser ablation from a geological target, the Jbilet Winselwan carbonaceous chondrite, then individually trapped using optical trapping, and subsequently analyzed by LIBS.

A set of complementary techniques, including SEM-EDX, XRD, and XRF, was employed to characterize the particle morphology, its elemental composition, and the mineralogy of the bulk material. Spherical particles produced by LA exhibited low polydispersity, with average diameters of 1.31 and 1.46 μm for matrix- and chondrule-derived particles, respectively.

Single-particle LIBS analysis enabled the discrimination of particles originating from Fe-rich matrix and chondrules based on characteristic intensity ratios (e.g., Mg/Fe, Na/Fe). Also, CN molecular bands were detected in some matrix-derived particles, thus indicating the presence of native organic carbon. In contrast, particles derived from the chondrule, a nonorganic domain, showed no detectable organic signal.

These findings demonstrate that μLA-OT-SP-LIBS can successfully characterize exiguous, discrete domains with negligible sample damage and absolute mass requirements in the low microgram range.

The proposed methodology provides a powerful platform for multielemental and molecular analysis of rare or valuable samples, with potential applications in meteoritics, geochemistry, and astrobiology.