Basic and practical analysis of LF-NMR and straightforward toolbox to its successful operation

• Extremely tight H-bonding in solids (such as ice) is not in a measurable range in LF-NMR. • Maintaining a prior stable temperature of the sample along with the NMR temperature is required. • Both H-bonding strength and quantity involve generating signal intensity. • Calibration of LF-NMR is mandatory to avoid common operating pitfalls. • Number of observations and scanning are required to reduce noises and artifacts. Low-field NMR (LF-NMR) gained popularity due to its diverse advantages, including non-destructive testing, plug-and-play operation (requiring only electricity), rapid analysis, affordability, simplicity, and portability. However, some users (students and new users) frequently face challenges in operating and obtaining scientifically sound results. Although operating LF-NMR is quite easy, improper calibration and failure to maintain surrounding conditions can lead to unreliable relaxation times. From practical experiences, this article aims to include necessary steps for its operation and guide users in troubleshooting common challenges. This contribution is structured to answer practical questions that the operator may have when using LF-NMR. For example, can LF-NMR be used when H-bonds are extremely tight? How can signal noises be minimized? Why are time intervals between observations necessary? Notably, prior incubation of samples at the operating temperature of the NMR (32 °C in this study) for at least 1 h effectively stabilized sample temperature, reducing fluctuations in relaxometry. Performing a minimum of two scans with multiple observations also minimized noise and artifacts. To make it a useful and easy practical guide, the results depicted in this study are based on real food systems such as egg yolk, honey, water, corn oil, and canola oil. Besides, sample selection is crucial to avoid using LF-NMR outside its applicable range; for instance, ice was unsuitable for detecting its T 2 relaxation time due to its extremely tight H-bonding. This guidebook avoids lengthy theoretical explanations; instead, rapid instructions from practical aspects of correct and incorrect situations are instructed to avoid common pitfalls.