A Novel Ultralow-Consumption Technique for Mafic Rock Major and Trace Element Analysis

In situ microanalysis techniques are indispensable for characterizing precious samples due to their ultralow sample consumption. However, their application to mafic rocks major/trace element analysis is hindered by inherent sample heterogeneity. To overcome this limitation, we developed an efficient infrared laser fusion sample preparation method. This novel pretreatment technique enables the processing of extremely small sample quantities (<1 mg) through laser-induced melting, facilitating effective single-particle homogenization. Validation against five reference materials (RMs) shows <10% discrepancy from recommended values for most elements, excluding the volatile elements Na, K, Zn, Pb, and Cu. Employing the established pretreatment method, two CE-6 basalt samples grains were converted to uniform glass beads, yielding major elements analytical precision (<2%, 1 s) and minimal deviation (<10%) for most trace elements. These results robustly confirm that this pretreatment homogenizes individual particles into compositionally uniform glass beads, rendering samples suitable for in situ microanalysis. Notably, analytical methods utilizing infrared laser heating can be performed concurrently with the sample homogenization process. This application eliminates potential discrepancies arising from grain-scale heterogeneity while enabling acquisition of systematic, multitechnique data sets from extremely limited sample size. Infrared laser fusion sample preparation method establishes a novel pathway to homogeneous microsample, unlocking comprehensive geochemical insights from single grain sample, providing a critical pretreatment method for planetary samples, including Lunar and Martian regolith.