WEST: an "all-terrain" multiple signal suppression technique for quantitative ¹H NMR

Area of Science:

• Nuclear Magnetic Resonance (NMR) Spectroscopy
• Analytical Chemistry
• Spectroscopic Techniques

Background:

• Quantitative NMR analysis often requires suppression of multiple signals, with the WET sequence being a common but less efficient method on high-field spectrometers.
• Existing saturation-based methods for signal suppression demand precise frequency adjustments and may not suppress satellite peaks or require specific hardware.
• A novel approach, WEST, is introduced to overcome the limitations of current NMR signal suppression techniques.

Purpose of the Study:

• To introduce and evaluate the WEST sequence for efficient and robust signal suppression in quantitative NMR analysis.
• To demonstrate the WEST sequence's effectiveness across various spectrometers and probe configurations.
• To highlight WEST's advantages over existing methods like WET in terms of efficiency and ease of use.

Main Methods:

• The WEST (Water suppression Enhanced through T1 effects) sequence was developed and tested.
• The method involves measuring the water frequency using standard proton acquisition and using it as the offset for the WEST spectrum.
• Performance was evaluated on three spectrometers from different manufacturers with varying magnetic field strengths and probe configurations.

Main Results:

• The WEST approach proved effective under diverse and challenging conditions, requiring only a 5-second water frequency adjustment.
• Suppression efficiency remained consistent despite minor shifts in frequency (5 Hz) and RF power (1 dB), demonstrating good repeatability.
• WEST achieved at least 93% solvent reduction, enhancing receiver dynamic range for analyzing target compounds and suppressing satellite peaks.

Conclusions:

• The WEST sequence is a robust and user-friendly tool for high-throughput 1H NMR, adaptable to various spectrometers.
• Its minimal adjustment requirements make it suitable for rapid analysis, as demonstrated with whisky samples.
• WEST has broad applicability beyond whisky analysis, including LC-NMR and matrix signal suppression for enhanced minor component detection.