Complementary Dual LC as a convenient alternative to multiple heart-cut 2D-LC for samples of medium complexity

Significance of the Topic

The analysis of moderately complex samples containing 15–30 components is critical in quality control, food and pharmaceutical industries. Conventional one-dimensional liquid chromatography (1D-LC) can struggle with resolution and selectivity when compounds are structurally similar or abundant. Two-dimensional LC (2D-LC) enhances separation power but often requires complex valve setups and increases analysis time, solvent use and dilution effects. Complementary Dual LC offers a streamlined alternative by running two orthogonal 1D-LC methods in parallel on a single instrument, improving throughput and quantitation for semi-complex mixtures.

Objectives and Study Overview

This technical note compares the performance of a complementary Dual LC approach, implemented on the Thermo Scientific Vanquish Duo UHPLC System, with a traditional multi-heart-cut 2D-LC workflow. A model mixture of 22 polyphenolic compounds from tea and olive oil was used to evaluate resolution, quantification precision, limits of quantification, analysis time, solvent and sample consumption.

Methodology and Data Acquisition

A systematic column screening identified Hypersil GOLD aQ and Accucore Polar Premium columns as complementary pairs. Method development produced two optimized 1D gradients (Method 1 and Method 2) for simultaneous parallel operation. For the 2D-LC setup, four heart-cut fractions were collected using a loop-based interface and processed with a fast second-dimension gradient (Method 3). Calibration curves (1–200 µg/mL) were acquired in triplicate.

Used Instrumentation

• Vanquish System Base
• 2× Vanquish Binary Pump H
• Vanquish Dual Split Sampler HT
• Vanquish Column Compartment H (×2)
• 2× Vanquish Diode Array Detector FG
• Loop interface with 6-port/2-position and 7-port/6-position valves

Main Results and Discussion

Complementary Dual LC resolved all 22 analytes with resolution ≥1.5 in at least one dimension, achieving an average retention precision of 0.011 % RSD and area precision of 0.221 % RSD. The average LOQ was 1.0 µg/mL. Multi-heart-cut 2D-LC achieved comparable retention precision but exhibited higher LOQs (2.6 µg/mL) and area RSD (0.806 %). Dual LC completed analysis in 14.1 min using 5.8 mL of mobile phase, whereas 2D-LC required 37.5 min and 63.8 mL. Dual LC also doubled sample throughput and halved sample consumption.

Benefits and Practical Applications

• Simplified method implementation without complex valve networks
• Enhanced throughput with parallel operation
• Lower solvent consumption and sample dilution
• Improved quantification precision and sensitivity
• Suitable for routine QC of moderately complex mixtures

Future Trends and Potential Applications

Advancements in detector sensitivity and integration of mass spectrometry could further enhance Dual LC capabilities. Automated method transfer and expansion to orthogonal column chemistries (ion exchange, HILIC) may broaden applicability. Miniaturization and on-line sample handling innovations could enable high-throughput screening in metabolomics and pharmaceutical impurity profiling.

Conclusion

Complementary Dual LC implemented on the Vanquish Duo system provides an efficient, precise and user-friendly alternative to multi-heart-cut 2D-LC for analyzing semi-complex mixtures. It delivers comparable separation power with significantly reduced analysis time, solvent use and dilution effects, making it well-suited for routine quantitative applications.

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