New Applications of Heart-Cut Multidimensional GC

Importance of topic

• Accurate identification and quantification in complex matrices is hindered by co-elution.
• Heart-cut multidimensional GC (MDGC) using a multi-Deans switch provides enhanced separation power by linking two capillary columns with distinct selectivities.

Objectives and study overview

• Demonstrate new applications of heart-cut MDGC with improved hardware design.
• Apply method UOP960 for trace-level analysis of oxygenated hydrocarbons (boiling point < 138 °C) in C4 liquefied petroleum gas.

Methodology and instrumentation

• Instrument setup:
  • Two-dimensional GC system with high-efficiency multi-Deans switch and two independent GC ovens.
  • Column configuration:
    • First dimension: Rtx-1 (15 m × 0.32 mm × 0.50 μm)
    • Second dimension: CP-Lowox (10 m × 0.53 mm × 10 μm) with midpoint restrictor (0.5 m × 0.32 mm)
• GC conditions:
  • Injection: 1 μL, injector temperature 280 °C, helium carrier gas (35 kPa, 0.91 mL/min), split ratio 10:1
  • First oven temperature program: 40 °C initial, ramp 10 °C/min to 250 °C, hold 4 min
  • Second oven temperature program: 50 °C hold 1 min, ramp 10 °C/min to 250 °C, hold 4 min
  • Detector: FID at 300 °C with helium makeup (20 mL/min), hydrogen (40 mL/min) and air (400 mL/min)
  • Switch settings: pressure 20 kPa, heart-cut window 0.25–5.68 min
• Software: fully integrated control for heart-cut selection via graphical user interface.

Main results and discussion

• No retention time shifts observed with multiple heart cuts, ensuring high reproducibility.
• Effective separation of co-eluting oxygenates such as dimethyl ether from LPG matrix demonstrated.
• Quantitative analysis showed excellent linearity and precision at trace levels.

Benefits and practical applications

• High retention time stability allows multiple cuts without time shifts.
• User-friendly software simplifies method development and heart-cut selection.
• Integration of two GC runs into a single cycle increases throughput.
• System cost approximately 20% lower than conventional two-valve MDGC setups.
• Suitable for quality control and trace analysis in industrial and research laboratories.

Future trends and potential applications

• Expansion to other volatile organic compounds beyond oxygenates.
• Integration with mass spectrometry and advanced detectors for enhanced identification.
• Automation of multiple heart-cut protocols for increased sample throughput.
• Development of more compact and robust switching hardware.

Conclusion

• Heart-cut MDGC offers a robust solution for resolving co-eluting compounds in complex matrices.
• Method UOP960 demonstrates reliable trace-level quantitation of oxygenated hydrocarbons in LPG.
• The streamlined workflow and cost-effective hardware make it attractive for diverse analytical applications.

Reference

• Zhuangzhi Max Wang, Clifford M Taylor, Richard R Whitney. New Applications of Heart-Cut Multidimensional GC. Shimadzu Scientific Instruments, Inc.