Simple sample transfer technique by internally expanded desorptive flow for needle trap devices.

Area of Science:

• Analytical Chemistry
• Environmental Science

Background:

• Needle trap devices (NTDs) are increasingly used for sampling volatile organic compounds (VOCs).
• Existing NTD sample transfer methods often require specific device configurations (e.g., 'side holes') or external desorptive flows.
• There is a need for simpler, more versatile NTD sample transfer techniques.

Purpose of the Study:

• To introduce and validate a novel, simple sample transfer technique for NTDs.
• To demonstrate the effectiveness of internal air expansion for thermal desorption without external flows.
• To evaluate the performance of this new method for analyzing specific VOC mixtures.

Main Methods:

• A new sample transfer technique for NTDs was developed, requiring no 'side holes' or external desorptive flow.
• NTDs were enriched with mixtures of benzene, toluene, ethylbenzene, and xylene (BTEX) or n-alkanes (C6-C15).
• Enriched NTDs were exposed to the hot zone of a gas chromatography (GC) injector, utilizing internal air expansion for desorption.

Main Results:

• The new method achieved clean and sharp desorption profiles for both BTEX and n-alkane mixtures.
• No carryover was observed for the analyzed VOCs under the tested conditions.
• The study investigated the impact of desorption temperature, time, and overhead volumes, finding minimal carryover (approx. 1%) for decane under moderate conditions.

Conclusions:

• A simple and effective sample transfer technique for NTDs has been demonstrated, relying on internal air expansion.
• This method eliminates the need for external desorptive flows and complex device modifications.
• The technique offers a promising alternative for efficient and accurate VOC analysis using NTDs.