dilution buffer for ap labeled 2nd antibody - (Mar/10/2007 )

Dear all
We use kpl AP labeled IgG in our experiment. We rehydrate it as it describled in your handbook. Now we want to use our homemade buffer to dilute it into working solution. So which buffer should we use. TBS or PBS ? Some one told me that PBS will inhibite the enzyme. if we should use TBS , how about the pH, should it be in 8.0---10.0?
Thanks a lot

Albert

I block the membrane in 5% skim milk, then use 1.25% skim milk in TBS-Tween (20 mM Tris (pH 8.0), 150 mM NaCl, 0.1% Tween 20) for dilution of both primary and secondary antibodies, with TBS-Tween washes after each antibody incubation step.