4.3.1. Log*D*pH7.4 Determination for [18F]6

A total of 25 μL of [18F]**6** was added to a mixture of 1-octanol and 0.02 M PBS (pH 7.4) in a 1.5 mL microtube. The mixture was shaken mechanically (500 rpm) for 10 min and centrifuged (1000 g, 5 min), and the layers were separated. A sample of 500 μL of each layer were pipetted into pre-weighed

polypropylene tubes and the activity in the samples was measured with a Wizard gamma counter. The distribution of [18F]**6** between octanol and PBS was calculated, according to

$$\text{LogD}\_{7.4} = \text{Log}\,\frac{\text{Ac}\_{\text{OCT}}}{\text{Ac}\_{\text{PBS}}}$$

where Ac*oct* = activity concentration of octanol and Ac*PBS* = activity concentration of PBS. Log*D*pH7.4 = 1.56 ± 0.20 (*n* = 5).
