Evaluation of solid-phase microextraction for time-weighted average sampling of volatile sulfur compounds at ppb...

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Air Quality Monitoring

Background:

• Volatile sulfur compounds (VSCs) are significant air pollutants.
• Accurate time-weighted average (TWA) sampling is crucial for monitoring VSCs.
• Solid-phase microextraction (SPME) offers a solvent-free extraction technique.

Purpose of the Study:

• To investigate the suitability of SPME for TWA sampling of five VSCs at ppb levels.
• To evaluate the influence of experimental parameters on SPME uptake rates.
• To determine the feasibility of using a Carboxen-poly(dimethylsiloxane) fiber for VSC sampling.

Main Methods:

• SPME with a Carboxen-poly(dimethylsiloxane) fiber was used for VSC extraction.
• Diffusion was controlled by retracting the fiber within the sampling device needle.
• Central composite face design was employed to study the effects of concentration, humidity, temperature, and extraction time.

Main Results:

• SPME uptake rates for hydrogen sulfide, methanethiol, ethanethiol, and dimethyl sulfide were significantly affected by multiple parameters, invalidating TWA sampling.
• Reverse diffusion of hydrogen sulfide, methanethiol, and ethanethiol occurred at 40% relative humidity.
• Dimethyl disulfide showed an 8% variation in uptake rate across the experimental domain, consistent with theoretical values, confirming SPME's suitability for its TWA sampling.

Conclusions:

• SPME with the specified fiber is a viable technique for TWA sampling of dimethyl disulfide.
• SPME is not suitable for TWA sampling of hydrogen sulfide, methanethiol, ethanethiol, and dimethyl sulfide under the tested conditions.
• No significant analyte loss was observed during storage for up to 3 days at -80°C.