soli TOC cube

soli TOC cube — Temperature-dependent differentiation of carbon in solids

Importance of the topic

The reliable separation and quantification of carbon fractions in solid materials (total organic carbon, inorganic carbon and elemental/residual oxidizable carbon) is essential across environmental monitoring, soil science, waste characterization, construction-material testing and quality control. Temperature-programmed approaches that distinguish carbon fractions by controlled thermal release offer robust fractionation without aggressive chemical pretreatments, reducing hazards and preserving sample integrity. Instruments that automate sample handling, provide short cycle times and deliver low detection limits expand throughput and applicability in routine and research laboratories.

Objectives and overview of the system

This datasheet presents the soli TOC cube, a benchtop elemental combustion analyzer designed to differentiate and quantify TOC, TIC and elemental (residual oxidizable) carbon by programmed temperature ramping. The instrument aims to: reduce sample preparation (no acid digestion required), automate sample and ash handling, shorten analysis times through active cooling, and deliver trace-level detection with integrated software control and data management features.

Methodology and analytical principle

The soli TOC cube uses a dynamically heated resistive vertical furnace with a continuous temperature program to thermally evolve carbon species from solid samples loaded into crucibles. Evolved CO2 is quantified using a CO2-specific infrared detector; total nitrogen (optional) is measured with an electrochemical cell sensitive to NO. The furnace couples to a straight quartz combustion tube filled with a platinum catalyst for post-combustion. Fractionation into TOC, TIC and ROC is achieved by timed temperature stages that target volatilization/combustion ranges of different carbon forms. Automated ash removal and active cooling enable rapid cycling and low maintenance.

Used instrumentation

• Analyzer model: soli TOC cube (Elementar Analysensysteme GmbH)
• Sample introduction: Vario Solid Sampler with radial 89-position turret and central rotating robotic sampler (random access)
• Sample holders: reusable steel and ceramic crucibles, up to 3 g / 3 ml capacity
• Furnace: robust vertical resistive heater, up to 900 °C, 28 mm ID quartz reaction tubes with platinum catalyst
• Ash handling: automatic ash removal via robotic sampler
• Cooling: active furnace cooling (fan) and system-level cooling for short analysis times
• Carrier gases: Oxygen with Nitrogen or Argon
• Detection: CO2-specific infrared detector (built-in, <20 ppm detection limit for CO2); optional NO-sensitive electrochemical cell for N
• Control and software: Fully digital control via external PC running Winvar proprietary software (Windows 7/8/10-compatible), features include matrix-independent multipoint calibration, LIMS integration, automated diagnostics, remote control and optional 21 CFR part 11 compliance

Key technical specifications and performance

• Quantification ranges: Carbon 0–50 mg absolute (or 0–100%); Nitrogen (optional) 0–20 mg absolute (or 0–15%)
• Limits of detection (approx.): C LOD <15 µg C absolute (IR detector); N LOD <20 µg N absolute (electrochemical cell, optional)
• Precision example: standard deviation <0.1% absolute for 100 mg CaCO3 and for a 100 mg soil standard
• Analysis time: ~25 minutes for a full temperature ramp (TOC/ROC/TIC) including optional TN; ~8 minutes for acidified samples; routines self-optimize to sample weight and element content
• Sampling capacity: 89-position non-stacked random access turret
• Power and utilities: 100/110/200/230 V, 50/60 Hz, 1.8 kW; gas consumption approx. O2 ~160 mL/min, N2 ~425 mL/min
• Size and weight: ~70 kg, footprint 67 x 55 x 106 cm (W x D x H including turret)
• Electronics and safety: fully digital electronics integrated into unit, conforming to EU Machinery Directive 2006/42/EG

Main results and discussion (system capabilities and advantages)

The soli TOC cube implements temperature-programmed differentiation to separate TOC, TIC and ROC without acid digestion, which preserves sample matrices and reduces consumables and chemical waste. The combination of a platinum-catalyzed post-combustion tube and a CO2-specific IR detector yields high sensitivity for carbon, suitable for low-µg quantitation in soils and construction materials. Automated sample handling (large random-access turret and robotic sampler) increases throughput and reproducibility; automatic ash removal minimizes operator intervention and maintenance downtime. Active cooling shortens cycle times compared with passive furnace cooldown and allows higher sample throughput in routine labs. Software-driven multipoint/multirange calibrations (matrix-independent for carbon fractions) simplify method setup across diverse sample types.

Benefits and practical applications

• Reduced sample preparation: no acids required for TOC/TIC/ROC fractionation, lowering risk and sample alteration
• High throughput: 89-position turret, rapid cooling and automated ash handling support routine laboratory workflows
• Low detection limits and robust precision: suitable for environmental, soil, waste and materials testing where trace carbon discrimination is needed
• Flexible operation modes: multiple analysis configurations (TOC/ROC/TIC, TOC/TIC, TOC/ROC, TN etc.) to match regulatory and research needs
• Integrated data management: non-manipulable raw data storage, LIMS integration and remote control enable QA/QC and regulatory compliance

Future trends and potential applications

Temperature-programmed combustion analyzers like the soli TOC cube are likely to see broader adoption in environmental monitoring, circular economy applications (waste-to-materials characterization), and forensic/materials research as regulators and industry demand detailed carbon speciation. Future enhancements may focus on: increased automation (robotic sample logistics), enhanced multi-element capability (expanded N and S detection options), miniaturized reactors for micro-samples, improved software analytics (machine-learning-based speciation deconvolution), and tighter integration with laboratory information systems and compliance workflows.

Conclusion

The soli TOC cube provides a compact, automated and sensitive platform for thermal differentiation and quantification of carbon fractions in solid samples. Its design emphasizes minimal sample preparation, high throughput and low detection limits while offering comprehensive software control and data integrity features that meet laboratory and regulatory needs. The instrument is positioned for routine and advanced applications where accurate partitioning of organic, inorganic and elemental carbon is required.

Reference

Elementar Analysensysteme GmbH. soli TOC cube — System Data Sheet. Elementar-Straße 1, 63505 Langenselbold, Germany. Phone: +49 (0) 6184 9393-0. May 2018.