Mitigation of solvent interference using a short packed column prior to ion mobility spectrometry

Area of Science:

• Analytical Chemistry
• Spectrometry

Background:

• Solvent interference is a significant challenge in direct sample injection for corona discharge-ion mobility spectrometry (CD-IMS).
• Existing methods often require complex sample preparation, limiting rapid analysis.
• Effective separation of solvent and analyte signals is crucial for accurate and sensitive detection.

Purpose of the Study:

• To develop a simple and inexpensive method to mitigate solvent interference in CD-IMS.
• To enhance the sensitivity, accuracy, and precision of CD-IMS analysis for pesticides.
• To enable direct sample injection without compromising analytical performance.

Main Methods:

• A short Teflon tube packed with squalene or OV-1 sorbent was placed between the injection port and the CD-IMS cell.
• This setup created a time delay, separating solvent and analyte introduction into the reaction region.
• Response surface methodology and central composite design were used to optimize sorbent parameters (amount, gas flow rate, temperature).

Main Results:

• A ~5s delay was achieved, allowing for effective proton removal by solvent molecules and enhanced analyte ionization.
• Analysis of organophosphorus pesticides (ethion, diazinon) demonstrated improved sensitivity, linearity, and repeatability.
• Direct injection using the proposed method yielded satisfactory results comparable to analyses without the pre-column.

Conclusions:

• The developed sorbent-based pre-column effectively overcomes solvent interference in CD-IMS.
• The simple, inexpensive methodology facilitates direct injection analysis with enhanced performance.
• This approach significantly improves the practicality and applicability of CD-IMS for pesticide detection.