Relaxation in water from different sources in Rome: Field testing a portable, center-field relaxometer.

With the ongoing miniaturization of nuclear magnetic resonance (NMR) instruments, smaller and smaller devices are being developed. Tabletop relaxometers first emerged in the early 1970's, and mobile stray-field relaxometers were introduced in 1980 for well logging and subsequently for nondestructive materials testing. Portable center-field NMR relaxometers are still in development stage. The performance of a commercial, miniature, center-field relaxometer was field-tested by comparing transverse 1H water relaxation decays from a variety of sources in Rome. With attention to reproducibility of measurements, the transverse 1H NMR relaxation times at a 20 MHz Larmor frequency were measured locally right after sampling in Rome, Italy, and later under controlled laboratory conditions in Davis, California, USA. Although functional, the reproducibility of the miniature relaxometer is highly temperature-dependent and requires well-controlled environmental conditions.