Metrohm 917 Coulometer “Spirit” – Integrated Karl Fischer Coulometric Moisture Analyzer

Overview

The Metrohm 917 Coulometer “Spirit” is a fully integrated, benchtop coulometric Karl Fischer moisture analyzer engineered for precision, safety, and operational efficiency in regulated laboratory environments. It operates on the fundamental electrochemical principle of coulometric Karl Fischer titration: water in the sample reacts stoichiometrically with iodine generated *in situ* at the anode via controlled electrolysis of iodide ions in the KF reagent. The total charge passed (Coulombs) is directly proportional to the mass of water quantified—enabling trace-level detection without volumetric reagent dispensing. Unlike volumetric systems, this method eliminates burette calibration drift and delivers inherently high reproducibility for low-water-content samples (10 µg–200 mg H₂O). The instrument integrates the generator/indicator electrodes, magnetic stirrer, sealed titration cell, reagent delivery and waste evacuation pumps, and a high-resolution touchscreen interface into a single compact housing—reducing footprint, cross-contamination risk, and operator intervention.

Key Features

• Fully automated coulometric titration with auto-sensing sample introduction: detects vial insertion or syringe actuation and initiates pre-titration and measurement without manual start commands.
• Integrated dual-mode capability: performs both coulometric Karl Fischer moisture determination and bromine number/bromine index analysis using the same electrochemical cell and reagent system.
• Onboard reagent management: continuously monitors cumulative reagent consumption, injection count, and estimated water load; triggers configurable alerts for reagent replacement to ensure analytical integrity and operator safety.
• Touchscreen-driven workflow: 90 mm × 120 mm high-contrast color display with real-time titration curves, status icons (e.g., KF ready/pre-titrated), and 14 user-defined quick-access method shortcuts.
• Touch-actuated reagent handling: built-in peristaltic pump enables one-button reagent addition and waste evacuation—no opening of the titration cell required, minimizing exposure to toxic/pyridine-free KF reagents.
• Comprehensive connectivity: two USB ports support direct connection to balances, printers, barcode scanners, and USB storage devices; Ethernet port enables LIMS integration, network-based PDF report generation, and centralized data archiving.
• Regulatory-ready architecture: supports audit trails, electronic signatures, and secure user access levels (Operator/Expert) when paired with Metrohm tiamo™ software and configured per FDA 21 CFR Part 11 and ISO/IEC 17025 requirements.

Sample Compatibility & Compliance

The 917 Coulometer “Spirit” is optimized for homogeneous liquid and soluble solid samples compatible with standard coulometric KF reagents (e.g., two-component anolyte/catholyte systems). For heterogeneous, thermally stable, or KF-reactive matrices—including polymers (PE, PP, PVC), lubricants, pharmaceutical excipients, and hygroscopic powders—the system is designed for seamless integration with optional Metrohm KF ovens (860 single-position or 885 18-position autosampler). These ovens employ headspace heating under dry carrier gas (N₂ or synthetic air), releasing bound water quantitatively and transporting it to the titration cell—eliminating direct sample contact with reagent and preventing side reactions (e.g., with aldehydes, ketones, or basic additives). All hardware and firmware comply with IEC 61010-1 safety standards; data integrity features align with GLP, GMP, and pharmacopeial guidelines (USP , EP 2.5.12, ASTM D6304).

Software & Data Management

Data capture and reporting are natively managed through the embedded operating system, requiring no external PC for routine operation. Each analysis generates a tamper-evident, digitally signed PDF report containing method parameters, raw titration curve, endpoint confirmation, calculated water content, drift correction values, and operator ID—all stored locally or exported via USB. When connected to a network, reports are archived automatically to designated servers or LIMS endpoints. The internal database retains full method definitions, calibration records, and result histories with time-stamped metadata. Optional tiamo™ software extends functionality to advanced statistical evaluation, multi-parameter method development, electronic signature workflows, and full 21 CFR Part 11 compliance—including role-based permissions, change tracking, and irreversible audit logs.

Applications

The 917 Coulometer “Spirit” serves as a primary moisture control tool across industries governed by strict water specification limits. In pharmaceutical manufacturing, it verifies residual moisture in lyophilized injectables, active pharmaceutical ingredients (APIs), and excipients per ICH Q5C guidelines. Petrochemical labs use it for water quantification in jet fuels (ASTM D6304), transformer oils (IEC 60814), and biodiesel blends. Food and beverage quality control relies on its accuracy for moisture in powdered dairy, coffee extracts, and freeze-dried formulations. Polymer producers apply it to monitor moisture in PET chips prior to extrusion—where even 50 ppm can cause hydrolytic degradation. Cosmetic R&D employs it for water activity assessment in emulsions and anhydrous formulations (e.g., lipsticks, sunscreens), while specialty chemical manufacturers use its bromine index mode to assess unsaturation in oleochemical feedstocks.

FAQ

Can the 917 Coulometer operate without a computer?
Yes. All core functions—including method execution, real-time curve display, result calculation, PDF report generation, and USB storage—are fully autonomous. A PC is only required for advanced tiamo™ software configuration or LIMS synchronization.
What is the minimum detectable water mass?
The system achieves reliable quantification down to 10 µg H₂O, with optimal accuracy (±0.3%) achieved at ≥1000 µg. Detection limit is constrained by background drift and cell conditioning—not instrument electronics.
Is bromine number analysis performed using the same electrode set?
Yes. The same dual-electrode cell and coulometric principle apply; only the reagent composition and titration endpoint algorithm differ. No hardware modification is needed to switch between moisture and bromine index modes.
How does the instrument handle high-drift samples like solvents or oils?
It supports manual, automatic, or disabled drift correction. For volatile matrices, users may configure pre-titration duration and drift stabilization thresholds before sample injection to minimize baseline interference.
Can method parameters be password-protected?
Yes. Operator-level access permits run-only execution, while Expert-level access—secured by configurable passwords—is required for method editing, calibration, and system settings modification.