Measurement of total water and bound water contents in human stratum corneum by in vitro proton nuclear magnetic resonance spectroscopy

The reliability of in vitro proton nuclear magnetic resonance (NMR) spectroscopy to specifically measure the water content of rehydrated human stratum corneum samples was assessed by comparison with the previously validated thermal desorption-mass spectrometry technique. The interest of proton NMR is that it can determine, in the same sample, both the amount of total water by recording the spectra at ambient temperature, and that of bound water (non-freezing water) by recording the spectra below 0 degrees C. Provided that enough samples of stratum corneum are analysed to average out the observed and well-known sample-to-sample variation, proton NMR may be of value in the evaluation of hygroscopic properties of raw materials for moisturizer formulations.     

Determination of fat and water content in vitro and in vivo by proton nuclear magnetic resonance

Proton NMR spectroscopy was performed on a series of pork samples containing varying proportions of fat and muscle and on a series of control and obese mice. Initial measurements were made using a 0.5 T (21 MHz) whole body imaging system and the results were expressed as the ratio of water and lipid hydrogen peak areas. With pork samples the NMR results correlated well with per cent water or lipid in the tissue (r = 0.99 for 20- and 50-g samples). For the mice the correlation between per cent water or lipid in the body and the NMR measurement was 0.92. Subsequent measurements were made using a 4.7 T (200 MHz) imaging/spectrometer from which separate integral values were obtained for the water and lipid hydrogen peaks. The separation of the water and lipid peaks was 3.5 ppm. For pork samples measured with the 4.7 T system the correlation between the peak area and the amount of water or lipid in the sample was 0.997 with the standard error of the estimate being ±0.72 g for water and ±1.00g for lipid. NMR imaging was used to determine the relative amount of fat and muscle in a cross-section of a control and an obese rat.