Radiello Diffusive Sampler for Monitoring 1,3-Butadiene and Isoprene in Workplace Air

Importance of the Topic

1,3-Butadiene and isoprene are widely used in the manufacture of elastomers and are classified as carcinogens by IARC. Accurate monitoring at low ppb levels is essential for occupational health protection and to manage explosion hazards in chemical plants.

Objectives and Study Overview

The article presents the development and validation of a passive diffusive sampling method using Radiello cartridges packed with Carbopack X, followed by two-stage thermal desorption and high-resolution GC-MS analysis, for quantifying 1,3-butadiene and isoprene in workplace air over an 8-hour work shift.

Methodology and Instrumentation

• Sampler assembly: Radiello diffusive body (RAD1202) fitted with a 4.8 mm stainless steel net cartridge containing Carbopack X.
• Sampling conditions: 8 h exposure, direct diffusion at ambient temperature and humidity; cartridges stored cold and analyzed within 24 h (up to 14 days with ≤10 % analyte loss).
• Thermal desorption: Primary desorption at 320 °C (6 min, 90 mL/min, split 3:1); trap cryofocusing at –20 °C on Tenax® TA; secondary desorption at 290 °C (1 min, 21 mL/min, split 26:1).
• Analysis: High-resolution GC-MS with proper column selection to separate C4 alkene interferences (1-butene, 2-butene isomers, isobutylene).
• Calibration: Gas syringe spiking of 1,3-butadiene into Carbopack X cartridges; liquid injection of isoprene standard solutions.

Main Results and Discussion

• Diffusive uptake rates (20 °C, 50 % RH): 30.5 ± 0.3 cm3/min for 1,3-butadiene; 41.2 ± 4.9 cm3/min for isoprene.
• Storage stability: ≤ 7 % loss for butadiene and ≤ 8 % for isoprene after 14 days at low temperature.
• Uncertainty assessment: Combined expanded uncertainty ~48 % under laboratory conditions (ISO GUM, EN 838) and ~37 % in field comparison with OSHA Method 56 (ISO 13752).
• Field validation: Excellent agreement (regression slope ≈ 1, negligible intercept) with solvent-desorption OSHA 56 results for 40 workers at ~18 °C and 75 % RH.
• Environmental effects: Uptake rates decrease significantly at high temperature (40 °C) and humidity (80 % RH); minimal impact at low temperature (5 °C).

Benefits and Practical Applications

• Sensitivity at ppb levels with low dilution compared to solvent extraction methods.
• Passive sampling reduces risk of handling pumps and explosive atmospheres.
• Compatible with standard two-stage thermal desorption GC-MS systems.
• Suitable for routine occupational monitoring in a variety of industrial settings.

Future Trends and Potential Applications

• Extension of diffusive sampling to additional volatile carcinogens and C4 hydrocarbons.
• Integration with portable TD-GC instruments for on-site analysis.
• Development of multi-analyte cartridges for simultaneous monitoring of VOC panels.
• Application of predictive models to correct uptake rates for temperature and humidity variations.

Conclusion

The Radiello passive sampler with Carbopack X and thermal desorption GC-MS delivers a robust, sensitive, and user-friendly solution for assessing workplace exposure to carcinogenic 1,3-butadiene and isoprene, meeting regulatory accuracy and safety requirements.

References

1. NIOSH Manual of Analytical Methods, 4th Edition.
2. OSHA Method 56, U.S. Department of Labor, 1985.
3. HSE MDHS 53/2 and 63/2, Health and Safety Executive, 2003.
4. Cocheo V., Boaretto C., Sacco P. Am. Ind. Hyg. Assoc. J. 57 (897-904), 1996.
5. Brown J., Shirey B. Supelco Technical Report, 2001.
6. EN 838:1995 Workplace atmospheres – Diffusive samplers for gases and vapours.
7. ISO GUM, ISO 5725:1994, ISO 13752 standards on measurement uncertainty and method comparison.