which compressibility use with buffer and NaCl 0.15 M

[RAlcalde]

Hi I have a little question. I use a phosphate buffer with NaCl 0.15 M in HPLC-SEC of a protein with 0.4 ml/min of flow rate. My hplc pump is a 2250 Bischoff and has a correction for compressibility, still now I used a compressibility as it was water but I think I am wrong. How can I know the correct number ? Do I suppose to use a less value than water ?
Thanks for your anserws.
QF Ricardo Alcalde

[tom jupille]

At that level of salt, the compressibility of water remains unchanged.