Introduction of a Multidimensional GC System

Significance of the Topic

Accurate detection and quantification of trace-level compounds in complex matrices such as refined petroleum, flavor and fragrance formulations, and environmental samples is critical for quality control, regulatory compliance, and product safety. Conventional one-dimensional gas chromatography often fails to resolve low-abundance analytes from coeluting matrix components. Multidimensional GC (MDGC) offers enhanced separation power and selectivity, enabling reliable analysis of target compounds at trace levels.

Objectives and Study Overview

This application note introduces the configuration and performance evaluation of a multidimensional GC system by Shimadzu. The study aims to demonstrate how heart-cutting MDGC improves resolution of analytes that coelute in the first dimension, evaluate the repeatability of retention times and peak areas under multiple heart-cut conditions, and illustrate practical separation of ether additives in gasoline.

Methodology and Instrumentation

The MDGC setup consists of two GC units (MDGC-2010) with independent ovens, a high-performance inert-surfaced switching element, and two flame ionization detectors. The first column (Rt-TCEP, 60 m×0.25 mm ID, 0.4 µm) operates under a temperature program optimized for broad-range hydrocarbon separation. Eluted fractions containing target analytes are heart-cut and transferred via differential pressure control (APC) to the second column (DB-1, 30 m×0.32 mm, 3.0 µm) for focused analysis. Split injection and helium carrier gas at defined pressures ensure consistent flow and minimal pressure fluctuation during switching.

Key Results and Discussion

Analysis of gasoline spiked with methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and diisopropyl ether (DIPE) revealed coelution with matrix constituents in the first dimension. Heart-cutting the targeted retention window into the second column achieved complete baseline separation of the three ethers. Repeatability tests using a standard mixture of benzene, toluene, ethylbenzene, xylenes, styrene, and cumene showed negligible variation in retention times (RSD ≤0.03 %) across zero to four heart-cut segments. Second-column analyses of retention times and peak areas over eight replicates yielded RSD values below 0.5 %, confirming the high precision of the Shimadzu switching mechanism.

Applications and Practical Benefits

• Trace-level quantitation of volatile additives in fuel and environmental samples.
• Enhanced resolution of coeluting compounds in complex matrices without extensive sample pretreatment.
• Robust method repeatability with minimal retention time drift, supporting quality assurance and regulatory requirements.

Used Instrumentation

• GC Units: MDGC-2010 with AOC-20i autosampler, GCsolution software
• Detectors: Dual FIDs
• Columns: First dimension – Rt-TCEP (60 m×0.25 mm, 0.4 µm); Second dimension – DB-1 (30 m×0.32 mm, 3.0 µm)
• Carrier Gas: Helium at 300 kPa; Switching Pressure: 120 kPa
• Injection: Split mode, 0.2 µL volume, inlet at 135 °C

Future Trends and Potential Applications

Advances in MDGC could include integration with high-resolution mass spectrometry for mass-selective detection, automated heart-cut optimization using real-time pressure and flow monitoring, and development of faster second-dimension separations through micro-bore columns or ultrafast temperature programming. Emerging needs in metabolomics, petrochemical analysis, and environmental monitoring will drive adoption of multidimensional approaches with enhanced sensitivity and throughput.

Conclusion

The Shimadzu MDGC system with heart-cut capability delivers significant improvements in separation efficiency and analytical precision for trace-level analytes in complex matrices. High repeatability of retention times and peak areas under multiple heart-cut conditions demonstrates the robustness of the switching mechanism. This technique reduces reliance on extensive sample cleanup and supports reliable quantitation of challenging compounds, offering versatile applications in research, industry, and quality control.

Reference

Shimadzu Application News No. G253, Introduction of a Multidimensional GC System.