Determination method for methyl iodide using diffusive sampler and capillary GC with thermal desorption injector and...

Area of Science:

• Analytical Chemistry
• Occupational Health and Safety
• Environmental Monitoring

Background:

• Methyl iodide (CH3I) is a volatile compound with potential workplace exposure risks.
• Accurate and reliable methods are needed for monitoring methyl iodide concentrations in occupational settings.
• Existing methods may lack the sensitivity, portability, or ease of use required for workplace assessments.

Purpose of the Study:

• To develop and validate a new method for determining methyl iodide in the workplace.
• To assess the performance characteristics of a diffusive sampler coupled with gas chromatography.
• To provide a tool for measuring both time-weighted average and grab sample concentrations of methyl iodide.

Main Methods:

• Development of a diffusive sampler using a glass tube packed with porous polymer beads.
• Utilized a capillary gas chromatograph with a thermal desorption cold trap injector and FID detector.
• Evaluated sampling rate, storage stability, and influence of environmental factors (temperature, humidity, wind speed).

Main Results:

• The developed diffusive sampler exhibited a sampling rate of 4.6 ml/h for methyl iodide.
• Environmental factors (temperature, humidity, wind speed) had negligible impact on sampling accuracy.
• Samples remained stable for at least two weeks without significant methyl iodide loss.

Conclusions:

• The developed method enables accurate measurement of methyl iodide in the sub-ppm to ppm range for time-weighted averages (2-6 hours).
• The system also facilitates the measurement of average concentrations over short periods (seconds) via grab sampling.
• This method offers a reliable and practical approach for workplace methyl iodide exposure assessment.