conditions and the coupling procedure previously reportedwas followed
[22]. Briefly, membranes (30) were immersed in a 200-ml
dye solution (10mg/ml) for 30min at 60 ◦C followed by the addition
of 50 ml NaCl aqueous solution (20 wt.%). This step enhances
the binding of the dye to the internal surface of the membranes.
After30min,20 mlNa2CO3 aqueous solution (25 wt.%)was addedto
accelerate the reaction between the dye and the membrane which
took place for 4 h at 80 ◦C. The dye-conjugated membranewas subsequently
washed with water (50–60 ◦C), 2M NaCl, methanol, 6M
urea andwater until the eluatewas free fromdye. Membraneswere
stored in 0.05M Tris–HCl (pH 7.0) at 4 ◦C prior to use.