METTLER TOLEDO C20S/C30S Coulometric Karl Fischer Moisture Analyzer
| Brand | METTLER TOLEDO |
|---|---|
| Origin | Switzerland |
| Instrument Type | Coulometric Karl Fischer Moisture Analyzer |
| Titration Mode | Fully Automated |
| Measurement Resolution | 0.1 mV |
| Water Content Range | 10 µg – 200 mg H₂O |
| Accuracy | ±0.3% (for samples containing >1 mg H₂O) |
| Minimum Dosing Increment | 0.1 mC |
| Titration Control Precision | 0.1 mC |
Overview
The METTLER TOLEDO C20S and C30S are high-precision coulometric Karl Fischer moisture analyzers engineered for trace-level water quantification in demanding laboratory and quality control environments. Based on the electrochemical generation of iodine at a platinum working electrode—per the stoichiometric principle of the Karl Fischer reaction (I₂ + SO₂ + H₂O + 3RN + CH₃OH → 2RN·HI + RN·HSO₄CH₃)—these instruments eliminate the need for volumetric reagent standardization, thereby enhancing method robustness and long-term reproducibility. Unlike volumetric KF systems, the C20S/C30S generate iodine *in situ* via controlled electrolysis of iodide-containing electrolyte, enabling direct quantification of water mass from charge passed (Faraday’s law: 10.72 mC ≡ 1 µg H₂O). This architecture delivers exceptional sensitivity down to <1 ppm (w/w) in solid, liquid, and gaseous matrices, with minimal baseline drift due to all-glass titration cell construction and optimized cell geometry.
Key Features
- Fully automated coulometric titration with integrated One Click™ workflow interface—enabling rapid method execution, user-specific shortcut configuration, and intuitive touchscreen navigation compliant with IEC 61000-4-2 ESD standards.
- All-glass titration cell design minimizing diffusion-related drift and ensuring stable baselines for low-moisture measurements (<10 µg H₂O).
- Choice of membrane-free or diaphragm-type electrolysis electrodes—membrane-free configuration eliminates catholyte handling, reduces maintenance, and maintains accuracy even at sub-ppm levels for non-reactive or low-conductivity samples.
- Solvent Manager module for fully automated reagent dispensing, waste removal, and solvent replacement—reducing operator exposure to hazardous KF reagents (e.g., imidazole-based solvents, SO₂, methanol) and supporting OSHA-compliant lab practices.
- LevelSens technology for real-time monitoring of reagent and waste levels—preventing overflow, cross-contamination, and instrument downtime through predictive fluid-level alerts.
- Integrated heating oven compatibility (up to 300 °C) with gas-phase extraction (GPE) support—enabling accurate moisture determination in thermally labile, viscous, or insoluble samples (e.g., polymers, pharmaceutical excipients, lithium battery materials) via carrier gas (dry air or N₂) transfer to the titration cell.
Sample Compatibility & Compliance
The C20S/C30S accommodates a broad spectrum of sample types—including hygroscopic solids (e.g., APIs, catalysts), volatile liquids (e.g., solvents, monomers), and gases (e.g., compressed air, SF₆)—without matrix-specific hardware modification. Method development aligns with ASTM E203, ISO 760, USP , and EP 2.5.12. Data integrity is ensured through audit-trail-enabled software meeting FDA 21 CFR Part 11 requirements (electronic signatures, immutable records, user access controls), and full GLP/GMP traceability including calibration logs, reagent lot tracking, and environmental condition stamping (temperature/humidity).
Software & Data Management
Powered by METTLER TOLEDO’s tiamo™ software (v3.5+), the system supports method templating, multi-user permission tiers, and automated report generation (PDF/CSV/XML) with embedded metadata (operator ID, timestamp, instrument serial, environmental conditions). All raw current/time data, titration curves, and endpoint detection algorithms (dynamic slope thresholding, second-derivative peak analysis) are stored in a relational database with automatic backup and export to LIMS via OPC UA or direct SQL integration. Electronic signatures comply with ALCOA+ principles for regulated environments.
Applications
- Pharmaceutical QC: Residual moisture in lyophilized proteins, tablet granules, and excipients per ICH Q5C guidelines.
- Electronics: Water content in Li-ion battery cathode/anode powders and electrolyte formulations—critical for SEI layer stability.
- Petrochemicals: Trace water in hydrocarbon streams, lubricants, and biofuels per ASTM D6304.
- Food & Beverage: Moisture in low-water-activity products (spices, dried fruits, powdered milk) where over-drying risks oxidation.
- Polymers & Composites: Bound vs. free water in epoxy resins, polyamide pellets, and carbon fiber prepregs affecting cure kinetics.
FAQ
How does coulometric KF differ from volumetric KF in practice?
Coulometric KF generates iodine electrochemically during titration, eliminating reagent standardization and offering superior precision below 100 µg H₂O. Volumetric KF relies on pre-standardized titrant delivery and is preferred for higher water content (>1000 µg).
Can the C20S/C30S analyze samples that degrade in methanol?
Yes—gas-phase extraction (GPE) allows thermal release of water without direct solvent contact, making it suitable for acid-sensitive or methanol-reactive compounds.
Is validation support available for regulated industries?
METTLER TOLEDO provides IQ/OQ documentation templates, performance qualification protocols, and on-site installation qualification services aligned with ISO/IEC 17025 and Annex 11 requirements.
What maintenance intervals are recommended for the electrolysis electrode?
Under typical usage (≤5 analyses/day), membrane-free electrodes require cleaning every 2–3 weeks; diaphragm electrodes need catholyte replenishment weekly and diaphragm inspection monthly.
Does the system support remote diagnostics?
Yes—via secure TLS-encrypted tiamo™ Cloud Connect, enabling real-time instrument health monitoring, firmware updates, and expert-assisted troubleshooting without local IT intervention.
