2024/09/19 by Josh P. Peters, Peters, Josh P., Sönnichsen, Frank D. +4
Biochemistry, Genetics and Molecular Biology · Chemical Engineering · Medicine · #Advanced MRI Techniques and Applications #Analytical Chemistry and Sensors #Chemical Physics (physics.chem-ph) #Electron Spin Resonance Studies #FOS: Physical sciences #Instrumentation and Detectors (physics.ins-det)
paper · pdf · doi:10.48550/arxiv.2409.16411
openalex publication_date 2024/09/19 · openalex created_date 2024/10/27 · openalex updated_date 2026/08/01
Novel methods and technology drive the rapid advances of nuclear magnetic resonance (NMR). The primary objective of developing novel hardware is to improve sensitivity and reliability (and possibly to reduce cost). Automation has made NMR much more convenient, but it may lead to trusting the algorithms without regular checks. In this contribution, we analyzed the signal and signal-to-noise ratio (SNR) as a function of the receiver gain (RG) for 1H, 2H, 13C, and 15N nuclei on five spectrometers. On a 1 T benchtop spectrometer (Spinsolve, Magritek), the SNR showed the expected increase as a function of RG. Still, the 1H and 13C signal amplitudes deviated by up to 50% from supposedly RG-independent signal intensities. On 7, 9.4, 11.7, and 14.1 T spectrometers (Avance Neo, Bruker), the signal intensity increases linearly with RG as expected, but surprisingly a drastic drop of SNR is observed for some X-nuclei and fields. For example, while RG = 18 provided a 13C SNR similar to that at a maximum RG of 101 at 9.4 T, at RG = 20.2 the determined SNR was 32% lower. The SNR figures are strongly system and resonance frequency dependent. Our findings suggest that NMR users should test the specific spectrometer behavior to obtain optimum SNR for their experiments, as automatic RG adjustment does not account for the observed characteristics. In addition, we provide a method to estimate optimal settings for thermally and hyperpolarized samples of a chosen concentration, polarization, and flip angle, which provide a high SNR and avoid ADC-overflow artefacts.