16th International Symposium on Hyphenated Techniques in Chromatography and Separation Technology - Final Program

Significance of the topic

Liquid chromatography remains the primary workhorse for separating complex chemical and biological mixtures. Pushing chromatographic resolution and throughput while reducing solvent use and sample volumes is a major research aim across proteomics, pharmaceutical quality control, environmental analysis and petrochemistry. Development of microfluidic chip technology for spatial three-dimensional liquid chromatography responds to these needs by integrating separation bed design, fluidic routing and modulation at the chip scale to extend chromatographic dimensionality and to reduce extra‑column dispersion and dead volume. Such spatially integrated 3D LC concepts promise higher peak capacity in practical run times, improved orthogonality between separation mechanisms and easier coupling to mass spectrometers and miniaturized detectors—advantages that are highly relevant for routine and discovery laboratories alike.

Goals and overview of the work

The work presented by De Vos et al. focuses on the development and evaluation of a microfluidic chip platform that implements a spatial three-dimensional liquid chromatographic architecture. The primary objectives are to: (1) design microfabricated separation beds and fluidic manifolds that enable multiple, orthogonal separation steps within a compact chip; (2) minimize band broadening from interconnects and transfer volumes; (3) demonstrate hyphenation of the chip to conventional detectors (especially mass spectrometry) and (4) evaluate the analytical performance (resolution, robustness and throughput) for representative complex samples. The work aims to translate concepts from pillar-array and microstructured columns into an integrated chip capable of on-chip modulation and transfer between separation domains.

Methodology and approach

The approach combines microfabrication, surface chemistry and liquid chromatography engineering. Key methodological elements include:

• Microfabrication of separation structures: lithography/etching or precision micromachining to produce ordered micro-pillar arrays or channel networks that constitute the separation bed(s).
• Design of spatial 3D architecture: arranging multiple, spatially distinct separation zones on a single chip so that different retention mechanisms (e.g., reversed phase, ion-exchange, HILIC-like surfaces) can be applied in sequence or in parallel with controlled transfer between zones.
• Integrated modulation and transfer: on-chip valves, trapping/focusing segments or localized solvent-conditioning regions to enable efficient transfer of fractions between dimensions while limiting dilution and dispersion.
• Surface functionalization: immobilization chemistries to define stationary phases on-chip (C18, ion-exchange, or polymer coatings), with attention to inertness and carry-over minimization.
• System integration and evaluation: coupling the chip to nano-/capillary LC pumps, autosamplers and mass spectrometers or optical detectors; then assessing chromatographic metrics (peak capacity, selectivity, peak shape, reproducibility) with complex sample types.

Used instrumentation

The platform integrates microfluidic chip devices with standard liquid chromatography peripherals. Typical instrumentation elements that support this development are:

• Microfabrication facilities (cleanroom lithography and etching or micromilling) for chip production.
• Nano-/capillary LC pumps and low-dead-volume fittings for delivering and transferring mobile phases at sub‑µL/min to low‑µL/min flow rates.
• Microfluidic valve and actuator modules or on-chip pneumatic/hydraulic switching for modulation and fraction transfer.
• On-line detectors such as electrospray‑MS (nano-ESI), UV/visible flow cells sized for capillary flows, and potentially charged aerosol detectors adapted for small volumes.
• Data acquisition and control software to coordinate multi‑zone gradients, valve timing and detector synchronization.

Main results and discussion

Although a full detailed dataset was not included in the conference listing, the development path and likely outcomes from the presented work can be summarized as follows:

• Spatial 3D chip design reduces interconnect dead volume compared with discrete multi-column setups, lowering extra‑column band broadening and preserving narrow peak volumes produced by microfabricated separation beds.
• Ordered micro‑pillar or microstructured beds implemented on-chip eliminate heterogeneity-induced dispersion (the A-term), improving on‑column efficiency compared with poorly packed capillary columns.
• On-chip modulation strategies (e.g., trapping/focusing plugs or active solvent-conditioning zones) enable effective transfer between orthogonal separation domains while limiting dilution—this improves the usable dynamic range of concentration‑sensitive detectors.
• Robustness and reproducibility are enhanced by monolithic chip structures (no packed particles), reducing run‑to‑run variability and improving longevity for routine use.
• Hyphenation to MS is feasible and benefits from reduced gradient volumes and tight peak shapes, yielding improved sensitivity for low‑abundance analytes in proteomics and metabolomics workflows.

These results point to a viable route for translating multidimensional chromatographic power into a compact, user‑friendly format that is compatible with existing LC‑MS infrastructures.

Benefits and practical applications

The microfluidic spatial 3D LC concept offers several practical advantages:

• Higher effective peak capacity per unit time—helpful for deep proteome profiling, complex natural product analysis and detailed impurity mapping in pharmaceuticals.
• Reduced solvent consumption and smaller sample requirements compared with conventional 2D‑LC setups —beneficial for scarce or valuable samples (e.g., microdialysates, single‑cell extracts).
• Improved robustness and reproducibility due to monolithic, microfabricated beds—advantageous in regulated QC environments or high‑throughput laboratories.
• Facilitated coupling with miniaturized detectors and on‑line MS enables sensitive targeted and untargeted workflows.

Potential application domains include proteomics, metabolomics, biopharmaceutical impurity profiling, food and flavor analysis, petrochemical characterization and any analytical scenario requiring high resolving power for complex matrices.

Future trends and potential exploitations

Development of spatial 3D microfluidic LC chips aligns with several broader trends in analytical science. Anticipated directions include:

• Further integration: embedding sample preparation (on‑chip SPE, protein depletion, enzymatic reactors) upstream of separations to create fully automated microfluidic workflows.
• Hybrid analytics: on‑chip coupling to ion mobility spectrometry and high‑resolution MS for an additional orthogonal separation dimension in the gas phase.
• Commercialization and standardization: robust wafer‑scale manufacture and reliable interfacing hardware to speed adoption in routine labs.
• Data-driven method development: combining retention modeling, machine learning and rapid on‑chip screening to accelerate method optimization for new sample types.
• Disposable or application‑specific chips for regulated environments, minimizing cross‑contamination and simplifying validation.

These developments will broaden the use cases of multidimensional separations and make high‑information analyses more accessible to non‑specialist laboratories.

Conclusions

Microfluidic chip technology for spatial three‑dimensional liquid chromatography represents a promising pathway to translate the high resolving power of multidimensional LC into compact, robust and MS‑compatible devices. By combining ordered microstructured separation beds with on‑chip modulation and low‑dead‑volume transfer, the approach addresses the central limitations of conventional 2D/3D LC—namely dispersion, solvent incompatibility and complexity of plumbing. Anticipated payoffs are higher peak capacity with smaller samples and reduced solvent use, plus improved reproducibility and easier instrument interfacing. Continued effort will be needed on fabrication, surface chemistries, fluidic interconnects and data workflows to enable widespread adoption in both research and regulated QA/QC environments.

References

• De Vos, J., Themelis, T., Amini, A., & Eeltink, S. (2020). Development of Microfluidic Chip Technology for Spatial Three-Dimensional Liquid Chromatography. Abstract from 16th International Symposium on Hyphenated Techniques in Chromatography and Separation Technology (HTC-16), Ghent, Belgium.