Diisocyanates by OSHA Method 42 on a Thermo Scientific™ Acclaim™ Mixed-Mode HILIC-1 as a Confirmation Column

Significance of the Topic

Diisocyanates such as toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) are key components in polyurethane production but pose severe inhalation hazards and carcinogenic risks. Accurate air monitoring is essential for occupational safety and regulatory compliance.

Objectives and Study Overview

This study evaluates the performance of a Thermo Scientific Acclaim Mixed-Mode HILIC-1 column as a confirmatory tool for analyzing diisocyanate derivatives using OSHA Method 42. The aim is to demonstrate alternative selectivity without altering the established mobile phase conditions.

Methodology

Samples containing derivatized diisocyanates were prepared by reacting analytes with 1-(2-pyridyl)piperazine according to OSHA protocols. Isocratic HPLC separation was performed under the following conditions:

• Mobile phase: 293 g acetonitrile, 625 g water, 0.77 g ammonium acetate (10 mM), pH adjusted to 6.0–6.2
• Flow rate: 1.00 mL/min
• Column temperature: 30 °C
• Injection volume: 10 µL

Instrumentation

The chromatographic system comprised:

• Column: Acclaim Mixed-Mode HILIC-1, 5 µm, 4.6 × 250 mm
• Pump: Dionex UltiMate LPG3400
• Sampler: WPS-3000 SL
• Detector: VWD-3400 UV at 254 nm (313 nm optional) with RF-2000 fluorescence (ex. 240 nm, em. 370 nm)

Main Results and Discussion

The Mixed-Mode HILIC-1 column achieved clear baseline separation and confirmation of three diisocyanate derivatives:

• 2,6-Toluene diisocyanate
• 2,4-Toluene diisocyanate
• 1,6-Hexamethylene diisocyanate

The retention times were reproducible, and peak shapes were sharp, confirming the column’s complementary selectivity.

Benefits and Practical Applications

The alternative column allows laboratories to perform confirmatory analyses without reformulating the mobile phase, simplifying method validation and accelerating routine air sampling workflows in industrial hygiene and quality control settings.

Future Trends and Potential Applications

Potential advancements include coupling the mixed-mode approach with mass spectrometric detection for enhanced specificity, exploring greener solvent systems to reduce environmental impact, and adapting the method for real-time monitoring technologies.

Conclusion

The Thermo Scientific Acclaim Mixed-Mode HILIC-1 column provides a robust confirmatory solution for OSHA Method 42 analyses, delivering reliable separation of diisocyanate derivatives with minimal method adjustments.

References

• OSHA Method 42: Diisocyanates by High-Performance Liquid Chromatography
• Thermo Fisher Scientific Application Note, 2009