Karl Fischer titration and near-infrared spectroscopy in perfect synergy

Importance of the topic

Reliable moisture determination is essential in pharmaceuticals, chemicals, food products, and materials science to ensure quality, stability, and compliance. Karl Fischer titration offers high selectivity for water content, while near-infrared spectroscopy (NIRS) delivers rapid, non-destructive measurements. Synergizing these techniques combines accuracy and speed, optimizing laboratory workflows and supporting robust quality control.

Objectives and overview of the white paper

This white paper presents new developments in moisture analysis by Metrohm. It demonstrates how coupling Karl Fischer titration with NIRS enhances sample throughput, streamlines method validation, and boosts productivity in R&D, QC, and production environments.

Methodology and instrumentation

Karl Fischer titration determines water via two redox steps involving methanol, sulfur dioxide, and iodine. Volumetric titration covers 0.1–100 % water, while coulometric mode handles 0.001–1 %. Samples are weighed or dissolved in KF-compatible solvents (excluding ketones/aldehydes), injected into the titration cell, and the endpoint is detected by a polarized platinum electrode.

NIRS measures molecular overtone and combination bands in solids, liquids, and slurries without preparation. Samples are placed in disposable glass vials, cuvettes, or slurry cups. Spectra are linked to KF reference values using multivariate calibration (e.g., partial least squares regression) in Vision Air 2.0 software.

Used instrumentation

• Metrohm Karl Fischer titrator with double platinum pin electrode
• High-precision syringe dosing system
• Near-infrared spectrometer with disposable vial and cuvette holders, slurry cup option
• Vision Air 2.0 software for spectral acquisition and multivariate model development

Main results and discussion

Combining KF titration with NIRS yields a validated calibration model that predicts water content rapidly and accurately. NIRS routine analysis takes under 60 seconds per sample, including internal standardization. Periodic cross-checks with KF titration ensure ongoing model reliability.

Benefits and practical applications

• Rapid, no-prep moisture screening with NIRS
• High accuracy and selectivity using KF titration for calibration and validation
• Adaptable to a wide range of sample matrices
• Enhanced laboratory throughput and reduced analysis costs

Future trends and applications

Integration of KF and NIRS into inline process analytics will enable real-time moisture monitoring. Advances in chemometric software and instrument miniaturization will expand multicomponent analysis, predictive maintenance, and digital quality frameworks.

Conclusion

The complementary use of Karl Fischer titration and near-infrared spectroscopy provides a powerful, flexible platform for moisture analysis. This dual approach combines the confidence of KF titration with the convenience of NIRS, addressing diverse laboratory needs and accelerating decision-making.

References

WP-023EN, Metrohm White Paper: Karl Fischer titration and near-infrared spectroscopy in perfect synergy, October 2017