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.