Fig 1.
The problems with sodium benzoate as a clamping agent. (left graph) Cells were clamped with either 40 µM nigericin or 30 mM sodium benzoate, and the 488/440 ratio intensities were plotted as a function of pH and overlaid on the in vitro calibration curve. Intracellular pH values determined from BCECF-AM fluorescence of E. coli MG1655 (top right) and MC4100 (bottom right) clamped with sodium benzoate at pHe 5.6, pHe 6.1, and pHe 7.2 were plotted. It is evident that pHe was not equal to pHi (see text). Modified from reference 2.