Experience with LECO CN Analyzers - Paco San Nicolás

Experience with LECO CN Analyzers — Practical summary

This summary synthesizes operational experience with LECO elemental analyzers used for carbon and nitrogen determinations at a high-throughput academic laboratory. It highlights practical performance, sample preparation workflows, quality aspects, and recommendations for routine use in soil, plant and organic-matter analysis.

Significance of the topic

The reliable determination of carbon (C), nitrogen (N) and total organic carbon (TOC) is central to agronomy, soil science, environmental monitoring and product quality control. Laboratories facing large sample loads require analyzers that deliver fast throughput, stable long-term performance, low maintenance burden and reproducible results. Practical experience with widely used instrumentation informs best practices for sample preparation, instrument maintenance, data quality control and workflow design, enabling accurate reporting and efficient operations.

Objectives and overview of the report

This text reports real-world experience from the Ionomics Service at CEBAS-CSIC, Murcia, Spain. The main aims are to describe instrument performance, sample types and preparation, throughput, maintenance demands, and the practical strengths and limitations observed while operating LECO CN analyzers in a multi-user, high-volume environment.

Methodology and routine workflow

The laboratory processes approximately 50,000 samples per year encompassing agricultural soils, plant tissues, composts, fertilizers and various organic materials. Two operational analysis streams are described:

• Total C and N (C/N): ~0.1 g of dry, finely ground sample is weighed into sample boats and measured directly on the CN analyzer according to sample nature.
• Total organic carbon (TOC): carbonates are removed by acidification using 2N hydrochloric acid applied on a heating plate; after carbonate removal the sample is dried and total carbon is measured to derive organic carbon.

Routine practices emphasize consistent sample drying and grinding to ensure homogeneity, careful weighing, and use of appropriate reference materials and blanks for quality control.

Used instrumentation

The laboratory’s instrumentation history and current configuration includes:

• Previous instrument: LECO TRUSPEC CN (used from 2009 until replacement).
• Current CN analyzers: LECO 828 Analyzer (replaced TRUSPEC in the most recent upgrade) and LECO 628 (primarily used for TOC analyses).

These instruments serve both the host research center and an extended user base including other CSIC centers, universities and private companies.

Main results and discussion

Operational findings based on prolonged, high-throughput use:

• Robustness and uptime: LECO analyzers show excellent mechanical robustness and reliability under heavy daily use. They tolerate high sample throughput with limited downtime when proper maintenance schedules are followed.
• Maintenance and ease of use: daily maintenance requirements are simple and quick; preventive maintenance yields stable performance and minimizes interruptions.
• Analytical performance: results demonstrate strong accuracy, repeatability and precision appropriate for routine C/N and TOC determinations across diverse matrices.
• Throughput and speed: analysis times are short, facilitating efficient processing of large sample batches.
• Adaptability: the instruments accommodate a wide variety of sample types typical for agronomic and environmental laboratories when sample preparation (drying, grinding, decarbonation) is properly controlled.

Operational caveats and considerations:

• Sample homogeneity is critical—small sample masses (~0.1 g) emphasize the need for fine grinding and thorough mixing to avoid subsampling error.
• Complete carbonate removal is necessary for accurate TOC; the described 2N HCl heating-plate procedure is effective but must be carefully controlled to prevent sample loss or contamination.
• Routine use benefits from a structured QC program: blanks, certified reference materials, replicates and regular calibration checks help detect drift or matrix effects.

Benefits and practical applications

Key practical advantages observed:

• High throughput capability supports large-scale monitoring programs, multi-user facilities and contract analysis services.
• Low operational complexity allows laboratory staff to manage instruments with standard training, reducing dependency on specialized technicians for day-to-day tasks.
• Versatility in sample types makes these analyzers suitable for soil testing laboratories, plant nutrient studies, compost and fertilizer characterization, and research where rapid elemental information is needed.

Practical recommendations for laboratories considering similar deployment:

• Implement standard operating procedures that specify drying, grinding, sample mass, and decarbonation steps adapted to your matrices.
• Plan preventive maintenance schedules and keep spare consumables/parts to minimize downtime given high sample volumes.
• Establish a QC program with certified reference materials representative of sample matrices and include routine checks for both CN and TOC workflows.

Future trends and opportunities

Potential developments and opportunities to improve workflows and data value include:

• Automation and sample handling: extended use of autosamplers or robotic front-ends to reduce manual handling and improve throughput and traceability.
• Integrated TOC workflows: instrument-integrated acidification or alternative non-acidic carbonate removal strategies could streamline TOC analysis and reduce manual steps.
• Data integration and LIMS connectivity: improved software interoperability for automatic data transfer, QC flagging and laboratory information management.
• Expanded analytics: coupling elemental analyzers with isotopic measurement capabilities or complementary sensors could add value for ecological studies and provenance analyses.
• Sustainability: optimized reagents and waste handling to reduce environmental impact of decarbonation steps.

Conclusion

Long-term operational experience at a busy institutional facility indicates that LECO CN analyzers (including the 828 and 628 models) provide reliable, fast and accurate C/N and TOC determinations for a broad range of agricultural and environmental matrices. Their robustness and straightforward maintenance make them well suited to high-throughput, multi-user laboratories when paired with rigorous sample preparation and QC procedures. Adopting automation, tighter data integration and improved sample workflows are logical next steps to further increase throughput and data quality.

Reference

San Nicolás, Francisco T. Experience with LECO CN Analyzers. Head of the Ionomics Service, CEBAS-CSIC, Murcia, Spain.