NITC Derivatives of Volatile Ethanolamines Using Normal-Phase Chromatography with Acclaim Mixed-Mode HILIC-1

Importance of the Topic

Volatile ethanolamines pose significant occupational health risks due to their toxicity and widespread use in industrial processes. Reliable air monitoring techniques are essential to ensure workplace safety, comply with regulatory standards and prevent chronic exposure.

Objectives and Study Overview

The study aims to evaluate the performance of a normal-phase chromatographic method for determining NITC derivatives of volatile amines. It compares the original OSHA methods (PV2018, 2111) with a novel Acclaim Mixed-Mode HILIC-1 column to assess improvements in separation efficiency and sensitivity.

Methodology and Instrumentation

The analytical procedure involves:

• Derivatization: Reaction of air-sampled amines with 1-naphthyl isothiocyanate (NITC) to form UV-active thiourea derivatives.
• Chromatography: Normal-phase separation on a Thermo Scientific™ Acclaim™ Mixed-Mode HILIC-1 column (3 μm, 3×150 mm) using an isooctane:isopropanol (80:20, v/v) mobile phase at 0.6 mL/min and 25 °C.
• Detection: Diode array detection (200–600 nm) with quantitation at 280 nm.

Used Instrumentation

The method employs:

• Thermo Scientific™ Dionex™ UltiMate™ 3000 LC system
• Acclaim Mixed-Mode HILIC-1 column (3 μm, 3×150 mm)
• Diode Array Detector configured for UV detection at 280 nm

Main Results and Discussion

The method achieved baseline separation of four key peaks: unreacted NITC and NITC derivatives of ethylenediamine, diethylenetriamine and triethylenetetramine. Compared with original OSHA approaches, the mixed-mode HILIC column provided equal or better resolution and reduced run times. The derivatives exhibited strong UV absorbance, enabling low detection limits and reproducible quantification.

Benefits and Practical Applications

This approach offers the following advantages:

• Enhanced chromatographic performance: improved peak shapes and shorter analysis times.
• High sensitivity and selectivity: UV-active derivatives enable accurate quantitation at low concentrations.
• Regulatory compliance: aligns with OSHA guidelines while offering methodological improvements.
• Versatility: applicable to routine workplace air monitoring in industrial hygiene laboratories.

Future Trends and Opportunities

Advancements may include coupling with mass spectrometric detection for improved specificity, automation of derivatization steps to increase throughput, exploration of alternative derivatizing reagents for broader analyte scope and miniaturized sampling devices for real-time monitoring.

Conclusion

The evaluated method demonstrates robust performance for monitoring volatile ethanolamines in workplace air. Use of the Acclaim Mixed-Mode HILIC-1 column enhances separation and detection capabilities compared to existing OSHA methods, supporting improved safety surveillance in occupational environments.