1. Maximizing NMR Sensitivity: A Guide to Receiver Gain Adjustment
- Author
-
Peters, Josh P., Hövener, Jan-Bernd, and Pravdivtsev, Andrey N.
- Subjects
Physics - Instrumentation and Detectors ,Physics - Chemical Physics - Abstract
Novel methods and technology drive the rapid advances of nuclear magnetic resonance. 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 to use than before, but it may lead to trusting the algorithms without regular checks. In this contribution, we analyzed the signal and SNR as a function of the receiver gain (RG) for 1H, 2H, 13C, and 15N nuclei on three devices. 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 and 9.4 T spectrometers (Avance Neo, Bruker), the signal showed the expected approximately linear increase with RG, but we found an unexpected, drastic drop of SNR for X-nuclei: For example, while RG = 18 provided a 13C SNR similar to that at a maximum RG of 101, the obtained SNR was 46% higher than at RG = 20.2. These unexpected results suggest that NMR users may want to calibrate spectrometer settings to obtain the optimum SNR for their experiments, as automatic RG adjustment does not account for the observed characteristics. In this context, 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 artifacts., Comment: main text 12 pages, 5 figures; supporting materials 12 pages, 3 figure
- Published
- 2024