Complete soil and sediment analysis

Importance of the Topic

Rapid, accurate elemental characterization of soils and sediments underpins geological exploration, environmental monitoring and contamination assessment. X-ray fluorescence (XRF) spectroscopy provides a non-destructive, high-throughput approach to quantify major oxides and trace elements across wide concentration ranges, from parts per million up to 100%. Modern sequential WDXRF platforms streamline analysis workflows and support diverse geochemical matrices with minimal sample preparation artifacts.

Study Objectives and Overview

This application note illustrates a comprehensive two-step methodology using the Thermo Scientific™ ARL™ PERFORM’X Series spectrometer to analyze geological samples. The goals are:

• Quantify major and minor oxides via fused-bead preparation.
• Determine trace and ultra-trace elements in pressed pellets.
• Demonstrate instrument performance in terms of precision, accuracy, detection limits and throughput.

Methodology and Instrumentation

Major/Minor Oxide Analysis

• Sample preparation by lithium borate fusion at 1 000–1 100 °C to form homogeneous glass beads, minimizing particle size, mineralogical and inhomogeneity effects.
• Calibration spans typical geochemical ranges for Na₂O, MgO, Al₂O₃, SiO₂, P₂O₅, SO₃, K₂O, CaO, TiO₂, Cr₂O₃, MnO and Fe₂O₃, with standard errors of estimate generally below 0.3%.

Trace Element Analysis

• Pressed pellets minimize dilution effects and allow quantification of 30 trace elements (Ag, As, Ba, Bi, Cd, Ce, Cr, Co, Cu, Se, Ti, Pb, Zn, Sn, Sb, W, Mo, Mn, Nb, Ni, V, Y, S, Sr, Te, Zr, Th, U, Rb, Hg) from low ppm levels.
• Typical detection limits range from 10 to 120 ppm, with precision better than 5 ppm and analysis times of 6–100 s per element.

Instrumentation

• Thermo Scientific ARL PERFORM’X Series WDXRF spectrometer, 4–9 analyzing crystals, 2 detectors, 6 primary beam filters and 4 collimators.
• 4200 W Rh X-ray tube with 50 µm Be window and low-current filament for long-term stability.
• Helium purge and LoadSafe Ultra protect optics and samples during liquid or pellet analysis.
• Completely digital goniometer and innovative OXSAS™ software for matrix correction, background subtraction and high-resolution spectra.

Main Results and Discussion

Major/minor oxide calibrations deliver linear responses across 0.2–99.7 wt.% concentration ranges with standard errors of estimate below 0.32 wt.%. Detection limits in a 40 s measurement typically range from 10 ppm (TiO₂, MnO, Fe₂O₃) to 120 ppm (Na₂O). Trace element analysis achieves LoDs from 8 ppm (Mn, Mo, Ag, U) up to 308 ppm (Pb), with precision within 1–4 ppm. Graphical scans demonstrate excellent spectral resolution, low background thanks to polarization, and efficient overlap correction. The instrument’s dynamic range, automation and digital optics ensure reproducible quantification of both abundant and minor constituents.

Benefits and Practical Applications

The ARL PERFORM’X workflow offers:

• High accuracy and precision for geological and environmental matrices.
• Wide dynamic range from ppm to 100 % for comprehensive elemental coverage.
• Sample throughput above 60 samples per hour with dual-loading capability.
• Robust safety features (LoadSafe Ultra, liquid recognition, helium shutter) to protect optics and samples.
• Automated software control for high-volume QA/QC, mineral exploration and contamination mapping.

Future Trends and Applications

Ongoing developments are expected to include expanded certified reference material libraries for niche matrices, integration of machine-learning algorithms for automated spectral interpretation, on-line coupling with sample preparation robots and remote instrument operation. Emerging portable WDXRF modules may bring field-deployable geochemical screening with performance closer to benchtop systems. Continuous improvements in detector technology and X-ray optics will drive lower detection limits and faster analysis times.

Conclusion

A two-step approach combining fused-bead and pressed-pellet preparations on the ARL PERFORM’X Series WDXRF spectrometer enables comprehensive soil and sediment characterization. The system delivers excellent accuracy, precision, detection limits and throughput, supporting a broad spectrum of geochemical and environmental applications.

References

No specific literature references were listed in the source document. All calibrations are based on internationally certified reference materials provided with the instrument.