OSHA Method 60 for Volatile Amines Using Normal-phase Chromatography with Acclaim Mixed-Mode HILIC-1

Importance of the Topic

Volatile amines such as ethylenediamine, diethylenetriamine and triethylenetetramine are common in various industrial processes and represent potential inhalation hazards in occupational settings. Accurate monitoring of these compounds in workplace air is crucial for ensuring compliance with safety regulations and protecting worker health.

Objectives and Overview of Method 60

The primary goal of OSHA Method 60 is to provide a reliable analytical protocol for sampling and quantifying volatile amines in air samples. This method employs a derivatization reagent, 1-naphthyl isothiocyanate (NITC), to form UV-active thiourea derivatives, which are then separated by normal-phase chromatography on a Mixed-Mode HILIC-1 column.

Methodology and Reagent Chemistry

The procedure begins by drawing workplace air through tubes containing NITC, trapping amines as thiourea derivatives. After extraction into an organic solvent, the sample is injected onto the chromatographic system. The reaction ensures selective conversion of primary and secondary amines into stable, UV-detectable products.

Used Instrumentation

• Column: Thermo Scientific Acclaim Mixed-Mode HILIC-1, 3 μm, 3 × 150 mm
• LC System: Thermo Scientific Dionex UltiMate 3000
• Mobile Phase: isooctane:isopropanol (80:20 v/v)
• Flow Rate: 0.6 mL/min; Temperature: 25°C; Injection Volume: 1.0 μL
• Detector: Diode Array Detector (UV, 280 nm)

Main Results and Discussion

The Mixed-Mode HILIC-1 column achieved clear resolution of four major amine-NITC derivatives: monofunctional NITC, ethylenediamine-NITC, diethylenetriamine-NITC and triethylenetetramine-NITC. Chromatograms demonstrated sharp peaks and reproducible retention times within a 6-minute run. The method's sensitivity and selectivity matched or exceeded the original OSHA protocol, facilitating reliable quantification even at low concentration levels.

Practical Benefits and Applications

This improved normal-phase procedure offers advantages such as faster analysis times, enhanced peak shape and compatibility with existing OSHA sampling tubes. It can be applied in routine occupational monitoring, industrial hygiene studies and quality control programs across chemical manufacturing, coatings and polymer production.

Future Trends and Potential Applications

Advancements may include coupling with mass spectrometric detection for increased sensitivity and confirmation, miniaturized sampling devices for on-site analysis, and expansion to a broader range of volatile amines and amine-containing volatile organic compounds.

Conclusion

OSHA Method 60 using Mixed-Mode HILIC-1 chromatography provides a robust, efficient and reliable approach for monitoring volatile amines in workplace environments, ensuring compliance with safety standards and protecting worker health.

References

• OSHA Method 60: Volatile Amines Using Normal-Phase Chromatography with Acclaim Mixed-Mode HILIC-1, Thermo Fisher Scientific PB20618_E, 2012.