Fast, simple analysis of soil and sediment according to German soil protection regulations

Significance of the Topic

The monitoring of trace heavy metals in soils is critical for protecting human health, ecosystems, and sustainable land use. Regulatory frameworks in the EU and Germany mandate sensitive, reliable, and high-throughput analyses to assess contamination levels at construction sites, agricultural areas, playgrounds, forests, and wastelands.

Objectives and Study Overview

This study evaluates the analytical performance of the Thermo Scientific iCAP PRO X ICP-OES Duo system for multielement soil analysis under German soil protection regulations. Two NIST standard reference materials (2709a Joaquin Soil and 2781 Domestic Sludge), real soil samples, and spiked matrices were analyzed. An interlaboratory comparison with ICP-MS data from Laboratorien Dr. Döring assessed method validity.

Methodology and Instrumentation

Soil samples and SRMs were digested following DIN EN ISO 13657 using microwave-assisted aqua regia (HCl/HNO3). The iCAP PRO X ICP-OES Duo, operated in axial iFR mode, employed a glass cyclonic spray chamber, concentric nebulizer, quartz Duo torch, and a CETAC ASX-560 autosampler. Calibration ranged from 10 to 10 000 µg/L in 7% aqua regia, with yttrium (1 mg/L) as internal standard. Method validation included limits of detection (LOD) and quantification (LOQ) determination, linearity checks (R² ≥ 0.9999), spike recoveries, and continuous calibration verification.

Main Results and Discussion

• LOD/LOQ values in the low µg/L range supported trace element detection requirements.
• Linear dynamic range of 0–10 000 µg/L ensured accurate quantification across regulatory thresholds.
• SRM recoveries ranged from 85 to 104% (except Ba), consistent with ±20% acceptance criteria.
• Spike recoveries for real soils fell within 80–120%.
• Internal standard recovery (Y) remained between 90–110%, indicating absence of matrix effects.
• QC standard recoveries (200 µg/L) stayed within 95–120% over an 8-hour robustness run.
• Interlaboratory data showed comparable results between ICP-OES and ICP-MS for most elements.
• Analysis time per sample was approximately 2 minutes, enabling high sample throughput.

Benefits and Practical Applications

The iCAP PRO X ICP-OES Duo system offers rapid, sensitive, and robust multielement soil analysis, meeting DIN EN ISO requirements. Its high throughput and minimal user intervention suit routine environmental testing laboratories, supporting regulatory compliance, remediation monitoring, and land development assessments.

Future Trends and Opportunities

Advancements may include tighter integration with ICP-MS for ultratrace elements, increased automation of sample preparation and data processing, portable or miniaturized ICP-OES platforms for field screening, and expanded method standardization for emerging contaminants.

Conclusion

The Thermo Scientific iCAP PRO X ICP-OES Duo system demonstrated excellent sensitivity, accuracy, linearity, and robustness for heavy metal analysis in soils. Results aligned with regulatory expectations and interlaboratory comparisons, establishing this technology as a reliable solution for environmental and industrial laboratories.

Reference

• DIN EN ISO 11885:2009 ― Determination of selected elements by ICP-OES.
• DIN ISO 22036:2009 ― Trace element determination in soil extracts by ICP-AES.
• DIN EN ISO 17294-2:2017 ― ICP-MS for selected elements including uranium isotopes.
• DIN EN 13657:2003 ― Waste digestion for aqua regia soluble fraction analysis.
• DIN 38402-A45:2014 ― Interlaboratory comparisons for laboratory proficiency testing.
• Bannick C.G. et al. (2000) Bodenschutz und Abfallverwertung ― Vorschriften und Regelwerke.
• Federal Soil Protection Act (BBodSchG) of 17 March 1998.