Metrohm Inline Sample Preparation

Significance of the topic

Ion chromatography is widely used for quantifying anions, cations and polar substances in diverse matrices. However, complex sample composition can impair column life, generate blockages and compromise accuracy. Automated inline sample preparation addresses these challenges by integrating filtration, dilution, dialysis, extraction, matrix cleanup and preconcentration directly into the IC workflow. This approach enhances reliability, traceability and throughput while minimizing manual handling and contamination.

Objectives and study overview

The primary goal is to present Metrohm’s Inline Sample Preparation (MISP) portfolio and demonstrate how its patented techniques fully automate each preparative step prior to IC analysis. Key objectives include:

• Eliminate manual filtration, dilution and cleanup steps.
• Ensure precise, traceable liquid handling with the 800 Dosino.
• Expand the analytical range to trace/ultratrace levels (ng/L).
• Enable analysis of solids, gases and combustion products.
• Demonstrate improved accuracy, precision and cost-effectiveness.

Methodology and instrumentation

MISP comprises a suite of inline techniques that can be combined or used individually:

• Inline Ultrafiltration: Automated removal of particles (>0.2 µm) via a dual-channel pump and filtration cell, extending column life and reducing carryover below 0.1%.
• Inline Dialysis: Patented stopped-flow dialysis separates colloids, proteins and macromolecules using a 0.2 µm membrane, achieving complete analyte recovery and minimal carryover (<0.2%).
• Logical Inline Dilution (MIDT): System-controlled dilution ensures samples always fall within calibration range, eliminating out-of-range errors and enabling automatic multi-point calibration with a single standard.
• Intelligent Partial Loop Injection (MiPT): Automated adjustment of injection volumes between 2 and 200 µL based on sample concentration, offering linear response and carryover below 0.001%.
• Intelligent Pick-up Injection (MiPuT): Precise aspiration of 4–60 µL samples with a coated-steel needle to avoid metal contamination and sample loss.
• Inline Extraction: Transfer of water-soluble analytes from nonpolar matrices into an aqueous phase, followed by inline dialysis for droplet removal.
• Inline Matrix Elimination: Cation-exchange rotor cartridge (SPM) removes uncharged and oppositely charged matrix components, suited for polar solvents and aggressive media.
• Inline Preconcentration (MiPCT): High-capacity trap columns concentrate analytes from 0.2 to 20 mL sample volumes, lowering detection limits to ng/L.
• Inline Neutralization and Cation Removal: Automated pH adjustment and transition metal removal for highly acidic, alkaline or metal-contaminated samples, enabling ultratrace detection.
• Inline Calibration: Preconcentration of µg/L standards on the trap column generates ng/L calibration points automatically, ensuring reliable ultratrace quantification.

In addition to the 800 Dosino and dual-channel peristaltic pumps, key instruments include the 940 Professional IC Vario platform, 858 Professional Sample Processor, 942 Extension Module Vario LQH for liquid handling, 815 Robotic Soliprep for solids, PILS for aerosols, MARGA for online gas/aerosol monitoring, and Combustion IC (CIC) for halogen and sulfur analysis in solids, liquids and gases.

Main results and discussion

Integration of MISP techniques yields:

• Consistent detection limits from g/L to ng/L for anions, cations, organic acids and carbohydrates.
• Precision coefficients of variation typically below 1% across all modes.
• Carryover reduction to <0.001% with MiPT and MiPuT, and <0.1% with filtration or dialysis.
• Traceable, fully automated workflows that eliminate manual filtration, SPE and external calibrations.
• Extended column lifetime due to effective particle and matrix removal.
• Flexible method development, combining multiple inline steps for complex matrices including drinking water, process effluents, fuel blends, biodiesel, food extracts, fermentation broths, body fluids, nuclear and semiconductor rinse waters.

Benefits and practical applications

Automated inline sample preparation delivers:

• Time savings through elimination of manual steps and faster sample throughput.
• Cost reductions in labor, consumables and instrument maintenance.
• Improved data quality with minimized contamination and precise liquid handling.
• Traceability of each preparation step for regulatory compliance.
• Expanded analytical scope to solids, aerosols, gases and combustion residues.
• Applications in environmental monitoring, water quality, industrial process control, QA/QC in pharmaceuticals and food, nuclear monitoring, petrochemicals, semiconductors and clinical research.

Future trends and applications

Advances are expected in self-optimizing systems that use real-time data to adjust preparative parameters automatically. Integration with artificial intelligence and remote monitoring will enable predictive maintenance and dynamic method adaptation. Coupling inline sample preparation with mass spectrometry or other detectors will further broaden the range of detectable analytes. The move toward miniaturized, field-deployable modules will support on-site and continuous monitoring in environmental and industrial settings.

Conclusion

Metrohm’s Inline Sample Preparation technologies transform ion chromatography by automating every preparative step, from filtration to calibration. The modular, patented solutions enhance accuracy, reproducibility and throughput while extending analytical capabilities into trace, solid, gas and combustion sample domains. This integrated approach reduces manual labor, minimizes contamination risks and opens new applications across science and industry.

References

No formal literature references were provided in the source document.