Liquid handling applied to automated sample preparation in liquid chromatography

Importance of Topic

Automated sample preparation is central to modern liquid chromatography, addressing demands for higher throughput, consistent reproducibility and reduced labor costs. Inline liquid handling enhances flexibility by automating tasks such as dilution, pH adjustment and derivatization, thereby improving overall efficiency in routine chemical analysis.

Objectives and Study Overview

This study evaluates the performance of a liquid handling extension module (Metrohm 872) integrated into an ion chromatographic system. Key goals include demonstrating precise inline dilutions for multi-point calibration, assessing carryover between injections and showcasing the module’s potential for various automated sample‐prep workflows.

Methodology and Instrumentation

The system combines:

• Metrohm 850 Professional IC AnCat
• Metrohm 858 Professional Sample Processor
• 872 Extension Module Liquid Handling with Dosino pumps, an external mixing vessel, peristaltic pump and selector/injection valves

Standard multi‐ion solutions were automatically diluted across a range of factors (1–50×) in an external vessel, then injected into a Metrosep C4 column (150×4.0 mm) at 0.9 mL/min, 30 °C, using 2.5 mmol/L oxalic acid eluent.

Main Results and Discussion

• Linearity and Precision: Six‐point calibration curves for lithium, sodium, potassium and ammonium across 0.2–10 mg/L yielded correlation coefficients of 1.0000 and RSDs below 0.15 %.
• Carryover: No detectable carryover was observed when injecting blanks immediately after a 10 mg/L standard.
• Recovery: Automated dilutions provided recoveries between 99.6 % and 102.9 % with RSDs typically below 1 % across all tested ions.
These findings confirm the module’s ability to produce highly accurate and reproducible calibration data without manual intervention.

Benefits and Practical Applications

• Streamlined Calibration: Automated multi‐point calibration from a single stock solution reduces preparation time and error.
• Flexible Workflows: Inline pH adjustment, reagent addition or pre‐column derivatization can be implemented without modifying hardware.
• Cost and Labor Savings: Reduced hands‐on time and minimized risk of contamination or human error.
• High Throughput: Ideal for routine QA/QC in pharmaceutical, environmental and industrial laboratories.

Future Trends and Opportunities

Advancements may include integration with ultrafiltration or solid-phase extraction modules, AI‐driven method optimization and real‐time data reporting. Further expansion of automated sample‐prep capabilities can support complex matrices, preconcentration steps and hyphenated techniques.

Conclusion

The Metrohm 872 Extension Module for liquid handling demonstrably enhances automated inline sample preparation in ion chromatography. It delivers precise dilutions, robust calibration and zero carryover while reducing manual workload. This setup opens avenues for versatile, high‐throughput applications across diverse analytical settings.

References

• No additional literature was cited in the original document.