a Concentration of H
in the water at each time point.The concentrations were measured immediately after preparation, and at 1 and 2 h after preparation. The error bars represent the mean and standard deviation (SD) for 5 independent measurements. b Concentration of H2 in the water with 1.6 ppm H2 (circle) or with 5 ppm H2 (square) at each time point. The concentrations were measured before drinking and every 5 minutes after drinking. The error bars represent the mean and standard deviation (SD) for 3 independent measurements.