851 Titrando

Importance of the Topic

Coulometric Karl Fischer titration is a cornerstone technique for precise water content analysis across industries such as pharmaceuticals, food quality, petrochemicals and polymer science. The elimination of volumetric reagents and direct electrochemical generation of iodine enhance accuracy and reproducibility, making systems like the 851 Titrando essential tools for modern analytical laboratories.

Objectives and Overview

This manual defines the configuration, installation and operation of Metrohm’s 851 Titrando, a modular, computer-controlled coulometric titrator. Key aims include safe setup, integration of peripherals (dosing units, stirrers, Touch Control or PC software), and detailed guidance on working with Karl Fischer reagents and sample types.

Methodology and Used Instrumentation

The 851 Titrando operates by generating iodine coulometrically in a methanolic electrolyte and endpoint detection via a polarized Pt double-wire electrode. It supports various titration and measuring modes (KFC, BRC) and dosing commands (ADD, EMPTY, PREP, LQH).

• Instrumentation:
  – 851 Titrando (titrator module)
  – 900 Touch Control or PC with tiamo software
  – MSB-compatible dosing devices (Dosino, Dosimat)
  – Magnetic stirrer or Ti Stand (rod or magnetic stirring)
  – Optional Remote Box for TTL I/O integration
  – Auxiliary devices: balance, printer, barcode reader via USB
  – Coulometer cell: generator electrode (with/without diaphragm), indicator electrode, temperature sensor

Main Results and Discussion

Practical commissioning yields stable baseline drifts (<4 µg/min) within 30 minutes for undiaphragm setups and ~2 hours for diaphragm electrodes. Conditioning overnight can facilitate low–trace measurements (<100 µg). System tests verify generator current stability up to 400 mA and indicator sensitivity at polarization currents down to 5 µA. Routine replaces of reagents and regular cleaning maintain analytical precision.

Benefits and Practical Applications

• Absolute water determination without titer adjustments
• Automatable workflows with sample changers and KF ovens for solids
• Integrated peripheral control via MSB and Remote Box for multisystem automation
• Flexible operation in standalone or PC-controlled modes

Future Trends and Opportunities

Advances in digital connectivity, cloud-based data management and fully automated robotic sample handling will further enhance throughput and traceability. Miniaturized coulometric cells and intelligent titration methods promise lower reagent consumption and extended operational diagnostics.

Conclusion

The 851 Titrando offers a robust, versatile platform for high-precision coulometric water analysis. Its modular architecture, comprehensive peripheral compatibility and user-friendly software support a broad spectrum of laboratory workflows, ensuring reliability and regulatory compliance.

Reference

No external references were provided in the source document.