Analysis of Lower Aliphatic Aldehydes using Nexis GC-2030

Significance of the Topic

The detection of lower aliphatic aldehydes in ambient air is essential due to their link to sick building syndrome and regulatory limits on indoor air quality. Accurate, trace-level monitoring supports occupational safety and environmental health assessments.

Objectives and Study Overview

This study aims to establish a reliable workflow for sampling, derivatizing, and quantifying C2–C5 aldehydes in air. Using 2,4-dinitrophenylhydrazine (DNPH) cartridges coupled with flame thermionic detection (FTD) on a Nexis GC-2030, the method seeks high sensitivity, selectivity, and reproducibility.

Methodology

A two-stage DNPH cartridge train collects air at 0.1 L/min over 24 hours, with an upstream ozone scrubber to prevent DNPH derivative degradation. Aldehyde-DNPH adducts are eluted with acetonitrile. To remove unreacted DNPH, eluate passes through a cation exchange resin then is back-extracted with ethyl acetate.

Instrumentation

• Gas Chromatograph: Shimadzu Nexis GC-2030
• Detector: Flame Thermionic Detector FTD-2030
• Autosampler: AOC-20i
• Software: LabSolutions LC/GC
• Column: Rtx-5 (30 m × 0.25 mm I.D., 0.25 µm film)
• Carrier Gas: Helium, constant linear velocity 41.7 cm/s
• Injection: Splitless (1 min), then split 1:30; volume 1 µL; injector at 200 °C
• Temperature Program: 80 °C (1 min) → 20 °C/min to 200 °C (10 min) → 5 °C/min to 250 °C
• Detector Conditions: 280 °C, H₂ 1.5 mL/min, air 145 mL/min, makeup He 27.5 mL/min, current 1 pA

Results and Discussion

Chromatograms of 1 µg/mL standards in ethyl acetate demonstrated baseline separation of acetaldehyde-DNPH isomers, propionaldehyde, isobutyraldehyde, n-butyraldehyde, and pentanal derivatives, including stereoisomeric pairs. The method exhibited clear peak resolution and minimal interference after cleanup, enabling reliable quantitation at trace levels.

Benefits and Practical Applications

This approach offers:

• High sensitivity for regulatory compliance in indoor air monitoring
• Robust sample cleanup to minimize matrix effects
• Compatibility with routine QA/QC and environmental surveillance

Future Trends and Prospects

Emerging directions include on-line DNPH derivatization integrated with GC-MS for real-time analysis, miniaturized sampling devices for rapid field screening, and advanced detectors to extend sensitivity to sub-ppb levels.

Conclusion

The presented DNPH cartridge-GC-FTD method on Nexis GC-2030 provides a reproducible, sensitive solution for trace analysis of lower aliphatic aldehydes in air, supporting health risk assessment and regulatory monitoring.

References

Shimadzu Application News No. G292, Analysis of Lower Aliphatic Aldehydes Using Nexis GC-2030, June 2017.