The concentration of isoflurane in the bath, as measured by GC/MS, is plotted against the nominal concentration of isoflurane achieved by dilution of ACSF saturated with isoflurane.

<p>For measured values, each point represents the average of two samples taken during each isoflurane exposure (at 2 and 5 min, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003372#pone-0003372-g004" target="_blank">Figure 4</a>). The range of values (grey shading) at each nominal concentration indicates the variability of bath isoflurane concentrations. This loss occurred consistently despite identical procedures for diluting isoflurane to nominal concentrations for each experiment.