Elemental analysis: CHNS/O characterization of solid and liquid fertilizers by the Thermo Scientific FlashSmart Elemental Analyzer

Importance of the topic

Chemical composition analysis of fertilizers is key for agronomic research and quality assurance.
Accurate determination of elements such as nitrogen, carbon, hydrogen, sulfur and oxygen informs nutrient management decisions and environmental monitoring of runoff water.

Objectives and overview

This study evaluates the performance of the Thermo Scientific FlashSmart Elemental Analyzer for characterizing both solid and liquid fertilizers.
It aims to demonstrate the system’s precision, accuracy and flexibility in determining CHNS/O content across a variety of samples and element concentration ranges.

Methodology

The instrument uses dynamic flash combustion for CHNS and NC determinations and pyrolysis for oxygen analysis.
Details include:

• Sample introduction via MAS Plus Autosampler for solids and AS 1310 Liquid Autosampler for liquids
• Tin capsules for combustion, silver capsules for pyrolysis
• Combustion reactor with oxidation catalyst and a secondary reactor for nitrous oxide reduction
• Gas separation using water traps, CO₂ traps and a GC column
• Detection by thermal conductivity detector (TCD)

Used instrumentation

• Thermo Scientific FlashSmart Elemental Analyzer with dual independent furnaces
• Thermo Scientific MAS Plus Autosampler for solids
• Thermo Scientific AS 1310 Liquid Autosampler
• EagerSmart Data Handling Software

Main results and discussion

The analyzer provided reliable element quantification with relative standard deviations typically below 1%:

• Nitrogen determination in solid fertilizers (e.g., urea, ammonium salts) at various weights (4–200 mg) yielded RSDs of 0.1–0.5%
• Liquid fertilizers analyzed via 100 µL injections showed RSDs below 1.1% for N content
• Simultaneous NC, CHNS and NCS analyses achieved consistent quantification across elements, demonstrating no matrix effects between solid and liquid samples
• Oxygen content measured by pyrolysis showed precise separation and detection of CO generated, with RSDs around 0.06–0.13%

These findings confirm the system’s repeatability, accuracy and lack of matrix interference, supporting its suitability for diverse fertilizer analyses.

Benefits and practical applications

• Fully automated workflow reduces operator intervention and enhances throughput
• Multi-element capability in a single run streamlines laboratory processes and lowers cost per analysis
• No use of hazardous chemicals or wet digestion preserves safety and reduces waste
• Compliance with official methods (AOAC, ISO, Italian regulations) ensures regulatory acceptance

Future trends and potential applications

Advancements may include integrating isotope ratio analysis and expanding to other agrochemical matrices.
Automation and AI-driven data interpretation will further improve throughput and decision-making.
Portable or miniaturized EA systems could enable on-site fertilizer monitoring and environmental assessments.

Conclusion

The FlashSmart Elemental Analyzer reliably performs CHNS/O determinations on solid and liquid fertilizers with high precision and minimal sample preparation.
Its versatility, automation and adherence to official standards make it a valuable tool for agronomy, quality control and environmental analysis.

References

• AOAC Official Method 990.13: Total nitrogen in fertilizers
• BS ISO 22241-2:2006: Determination of urea content by total nitrogen
• Italian Official Method 146 (Gazzetta Ufficiale): New regulations for fertilizer control