PIPES acide libre, poudre blanche

PIPES is a zwitterionic N-substituted aminosulfonic acid "Good" buffer. Buffers can be made by adding a solution of base to PIPES free acid, titrating to the appropriate pH, or by mixing equimolar solutions of the sesquisodium salt and the disodium salt or dipotassium salt, titrating to the appropriate pH.

Zwitterionic Buffer, Effective buffering range: 6,1 - 7,5 (Merck Index reports 6,0 to 8,5 ), ΔpK/ΔT: 0,0085, pKa: 6,8 at 25 °C ; 6,66 at 37 °C

PIPES is used to buffer glutaraldehyde fixative solutions when fixing plant and/or animal tissue tissue samples. This will help prevent the loss of lipids. It is used to buffer glutaraldehyde and formaldehyde when fixing fungal zoospores for fluorescence microscopy and electron microscopy.

PIPES free acid is not very water soluble (approximately 1 g/l at 100 °C) but will solubilise in 0,5 M NaOH; PIPES salts are water soluble (usually resulting in clear, colourless solutions).