Accurate and fast analysis of 45 compounds, trace metals and a few rare earth elements (REE) in soils and sediments

Soil and sediment analysis plays an important role in environmental monitoring, geochemistry, land assessment, contamination screening, and resource evaluation. Because soils can contain a complex mixture of nutrients, minerals, trace metals, and potentially toxic elements, laboratories require analytical methods that can quantify a broad elemental range with reliable accuracy, precision, and throughput. Elements such as arsenic, cadmium, lead, chromium, nickel, copper, zinc, uranium, thorium, and selected rare earth elements can provide important information about sample origin, environmental impact, and material composition.

This application note examines the use of energy-dispersive X-ray fluorescence spectroscopy (EDXRF) for the analysis of 45 compounds and elements in soil and sediment samples prepared as pressed powder pellets. It focuses on the quantification of major oxides, minor constituents, trace metals, and selected rare earth elements using the Revontium™ Heavy Element edition benchtop EDXRF spectrometer.

The Analytical Challenge in Soil and Sediment Testing

Soil matrices are inherently complex. A single sample may contain high concentrations of silicates, aluminum and iron oxides, alkaline and alkaline earth elements, halogens, transition metals, heavy metals, and low-level trace elements. This complexity can create spectral overlaps in XRF analysis, especially when multiple elements are present across a wide concentration range. Accurate quantification therefore depends on optimized excitation conditions, stable sample preparation, robust calibration, and software capable of resolving overlapping peaks.

Another challenge is analytical efficiency. Laboratories often need to screen or quantify many elements in a single workflow without relying on multiple separate methods. A benchtop EDXRF approach can support multi-element analysis with minimal sample preparation, making it useful for routine soil and sediment characterization where speed and consistency are important.

Technical Background: EDXRF for Multi-Element Soil Analysis

EDXRF is a non-destructive elemental analysis technique that measures characteristic fluorescent X-rays emitted by a sample after excitation by an X-ray source. The resulting spectrum can be used to identify and quantify elements from light major components through heavier trace elements. In this study, measurements were performed using a Revontium Heavy Element edition EDXRF spectrometer equipped with a 50 W X-ray tube, an Ag anode, primary and secondary filters, four high-resolution silicon drift detectors, a spinner, and an automatic sample changer. Measurements were performed under vacuum using an oil-free dry vacuum pump.

The method was developed to quantify 45 compounds and elements, including major oxides such as Na₂O, MgO, Al₂O₃, SiO₂, K₂O, CaO, TiO₂, MnO, and Fe₂O₃, as well as trace elements such as As, Cd, Pb, Cr, Ni, Cu, Zn, Rb, Sr, Zr, Nb, Mo, Sb, Ba, Th, and U. Selected rare earth elements, including La, Ce, Nd, and Sm, were also included.

Methodology Overview

The calibration was established using 42 soil and sediment certified reference materials, including GSS, GSR, and GSD geochemical reference materials, along with NIST SRM 2709, 2710, and 2711. Additional Pro-Trace setup samples produced by Malvern Panalytical were also used. Standards and samples were oven dried, pulverized in a planetary ball mill with a wax/styrene additive, and pressed into pellets using a hydraulic press.

Five optimized measurement conditions were used to excite different groups of elements. These conditions covered light elements such as Na, Mg, Al, and Si; elements including P, S, Cl, K, Ca, Sc, Ti, and V; transition metals such as Cr, Mn, Fe, Co, Cu, Ni, and Zn; heavier trace elements including As, Se, Rb, Sr, Y, Zr, Mo, W, Pb, Bi, Th, and U; and additional elements such as Cd, Sn, Sb, Te, Cs, Ba, La, Ce, Nd, and Sm. The total measurement time per sample was 21 minutes, with the option to adjust measurement time depending on analytical requirements.

Key Topics Covered in the Full Application Note

• EDXRF method setup for 45 compounds and elements in soil and sediment matrices
• Pressed powder pellet preparation using dried, milled samples and binder additive
• Use of certified reference materials for calibration across a broad concentration range
• Optimized excitation conditions for light elements, transition metals, heavy elements, and selected REEs
• Software-based spectral deconvolution for resolving overlapping XRF peaks
• Calibration performance, root mean square values, correlation coefficients, and lower limits of detection
• Accuracy and precision assessment using certified reference material GSS5
• Practical considerations for low-level elements such as Cd and Sm when longer measurement times are required

Technology Relevance

The Revontium EDXRF approach is relevant for laboratories that need broad elemental coverage from a single prepared soil or sediment pellet. The combination of multiple silicon drift detectors, vacuum measurement conditions, optimized filters, sample spinning, and spectral deconvolution supports analysis of complex matrices containing both high-concentration oxides and trace-level metals. This makes the technique applicable to environmental laboratories, geochemical studies, mining and exploration workflows, and routine material characterization where fast multi-element screening is required.

The full application note provides detailed calibration information, detection limits, and accuracy results for the individual compounds and elements evaluated. It also explains how measurement conditions were selected and how the method can be adapted when lower limits of detection are required for specific elements.

Register to download the full application note and review the complete methodology, calibration data, detection limits, and accuracy results for EDXRF analysis of soils and sediments using Revontium.