Guide to Semi-Quantitative Non-Targeted Screening Using LC/ESI/HRMS.

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Chromatography

Background:

• Non-targeted screening (NTS) via LC/ESI-HRMS is a powerful alternative to targeted analysis.
• Quantifying all compounds in NTS is challenging due to the lack of analytical standards.
• Semi-quantification strategies are essential for estimating unknown compound concentrations.

Purpose of the Study:

• To provide strategies for semi-quantification in NTS.
• To identify factors affecting signal intensity in NTS.
• To discuss methods for improving NTS performance and enabling retrospective analysis.

Main Methods:

• Utilizing reversed-phase liquid chromatography with electrospray ionization high-resolution mass spectrometry (LC/ESI-HRMS).
• Employing semi-quantification strategies for unknown compounds.
• Combining positive and negative ionization modes to enhance detection.

Main Results:

• Signal intensity is influenced by sample preparation, ionization, and data processing.
• Simpler methods in sample preparation and chromatography generally yield better NTS results.
• Dual ionization modes (positive and negative) improve overall NTS performance.

Conclusions:

• Careful consideration of each analytical step is crucial for accurate semi-quantification in NTS.
• Optimized NTS protocols enhance compound detection and enable retrospective analysis.
• A checklist for semi-quantitative NTS is provided to guide researchers.