Dual-line Gas Analysis Using a Nexis GC-2060 Gas Chromatograph with a GI-30 Auto Gas Injector and BID and TCD Detectors

Significance of the topic

Gas analysis is essential across environmental monitoring, energy and resource management, and industrial process control. Accurate, repeatable quantification of inorganic gases (H2, N2, CO, CO2) and light hydrocarbons (CH4, C2 species) across widely varying concentration ranges (ppm to percent) is critical for safety, regulatory compliance, and process optimization. Combining detectors and automated sampling extends dynamic range, reduces operator burden, and improves data quality for continuous and high-throughput workflows.

Objectives and overview of the study

This application note demonstrates dual-line gas analysis on a single Nexis GC-2060 gas chromatograph equipped with two GI-30 auto gas injectors and two detectors (Barrier Discharge Ionization Detector, BID, and Thermal Conductivity Detector, TCD). Goals were to: enable simultaneous measurement of low- and high-concentration gas streams, evaluate detector complementarities (BID vs TCD), validate automated sampling repeatability with the GI-30, and illustrate carrier gas strategies for H2 detection.

Used Instrumentation

Instruments and major hardware used in the work:

• Nexis GC-2060 gas chromatograph (Shimadzu).
• Two GI-30 auto gas injectors (1 mL loop, heated valve and loop maintained at 80 °C, optional valve purge).
• BID (Barrier Discharge Ionization Detector) — He plasma ionization, single-filament He plasma collector.
• New single-filament (switching) TCD introduced in 2025 — shortened stabilization and improved sensitivity/linearity.
• Injection units: SPI (split/splitless) for BID line and SPL for TCD line.
• Micropacked-ST column (specified as 2.0 m × 1.0 mm I.D.; inputs referenced to 250 m × 0.50 mm I.D., df = 15 µm for flow calculations).

Methodology

Dual independent GC lines were configured on one Nexis GC-2060: Line 1 (SPI/BID) for trace-level analysis and Line 2 (SPL/TCD) for higher concentration analysis. Common GC temperature program: 35 °C (2.5 min) ramp 20 °C/min to 250 °C (hold to 26.75 min). Typical injection conditions: 150 °C injector temp, split mode, split ratio 4.0, column flow 7.0 mL/min, detector temp 260 °C. BID discharge gas flow was 50 mL/min; TCD makeup flow 2.0 mL/min and reference flow 50 mL/min. Carrier gas choices: He for most analyses; for H2 detection by TCD, N2 or Ar carriers were used. Two standard mixed gases were measured simultaneously: 10 ppm mix (He balance) on the BID line and 1000 ppm mix (He or N2 balance) on the TCD line.

Main results and discussion

Detector complementarity and concentration coverage:

• BID delivered high sensitivity at low concentrations (ppm level), detecting low-level components including H2 without switching carrier gas from He.
• TCD provided robust detection of higher-concentration components (up to percent levels) and detects all analytes except the chosen carrier gas (TCD can detect components that FID is insensitive to).
• Using both detectors in parallel enabled simultaneous measurement of a 10 ppm and a 1000 ppm standard on a single GC.

H2 detection specifics:

• BID using He carrier allowed simultaneous H2 and other components without carrier switching.
• TCD required changing carrier gas to N2 or Ar to detect H2; with Ar carrier, non-O2 components were detected concurrently with H2.

Sensitivity and stabilization:

• The new single-filament switching TCD demonstrated very high S/N and fast baseline stabilization after startup, enabling near-immediate analysis.
• Measured signal-to-noise (S/N) values for a 1000 ppm standard showed strong responses across compounds; S/N varied with carrier gas choice (He, Ar, N2), reflecting detector and carrier interactions.

Repeatability and automation:

• The GI-30 auto injector delivered excellent repeatability for continuous automated gas introduction. Peak area %RSD for both lines was < 0.5% across tested components (N = 5), confirming high precision comparable to automated liquid injection.
• Optional valve purge reduced ambient air intrusion, improving accuracy for atmospheric constituents (N2, O2) and trace analytes. Maintaining loop and valve at 80 °C minimized water condensation and stabilized sample volumes.

Benefits and practical applications

Key advantages demonstrated:

• Expanded dynamic range on a single instrument by combining BID and TCD: ppm-level sensitivity and percent-level robustness.
• Dual GI-30 configuration supports two independent sample lines with separate injection units, columns, detectors and carrier gases, enabling parallel analysis of samples with distinct matrices and concentrations.
• Automated continuous sampling reduces operator workload, improves throughput, and enhances reproducibility for routine monitoring, QA/QC and process control.

Typical application areas include environmental air monitoring, clean energy and hydrogen analysis, combustion/emissions testing, industrial gas QA and research workflows requiring simultaneous multi-concentration measurements.

Future trends and possibilities of use

Anticipated developments and practical extensions:

• Broader adoption of fast-stabilizing TCD designs and further detector sensitivity improvements to shorten analysis startup time and increase flexibility for online monitoring.
• Integration of multi-line GC configurations with automated sampling for real-time process monitoring and environmental sensor networks.
• Enhanced software workflows (batching, remote control, automated calibration) to support long-term unattended operation and data integrity for regulatory programs.
• Combining gas sampling automation with complementary sampling interfaces (e.g., thermal desorption, preconcentration) to extend detection limits and address trace contaminants.

Conclusion

Implementing two GI-30 injectors with BID and TCD on a single Nexis GC-2060 enables flexible, high-throughput gas analysis across wide concentration ranges. The BID provides ppm-level sensitivity (including H2 with He carrier), while the TCD offers stable measurement at higher concentrations and benefits from the new single-filament design for rapid stabilization. The GI-30 delivers automated, highly repeatable gas introduction (<0.5% RSD), reducing manual workload and improving data consistency. This configuration is well suited for laboratories requiring simultaneous analysis of diverse gas streams with differing concentration ranges and matrices.

Reference

Hikaru Inada and Natsuko Kanno. Dual-line Gas Analysis Using a Nexis GC-2060 Gas Chromatograph with a GI-30 Auto Gas Injector and BID and TCD Detectors. Shimadzu Corporation, Application News, First Edition: April 2026. Report No. 01-01171-EN.