1. Further evidence that the uptake of [“C jhexylamine, determined by centrifugal filtration of spinach chloroplast thylakoids through silicone fluid layers, gives precise estimations of light-induced H’ concentration gradients (ApH) is presented. ApH was independent of the amount of thylakoids used or of the concentration of hexylamine. Moreover, hexylamine uptake was sensitive to the osmolari...

The glass electrode is the most commonly used device to access the pH of an aqueous solution. It attains highly accurate measurements via simple and well-established procedures. However, the reasons why the glass electrode potential scales with hydrogen ion concentration according to almost Nernstian potential values have been long-standing challenges to explain. Only in the past 50 years has a...