Question on calibration & solvent strength .

[Ronaldo]

Hi Folks ,

I am using isocratic RP-HPLC , 65% methanol /water , flow rate 1ml/min ,column 250mm 4.6 id . i build up my calibration graph and use it for more than one year which was very time consuming . My question is , if i increase the solvent strength to 75% with keeping every things the same will i be able to use the same calibration curve with relating any unknown conc. from 75% to the calibration of 65% .In other wrod , i change only the mobile phase strength .

[danko]

The shortest answer, that is still adequate is: No!
You'll have to document the validity of your results once again.

Another story is, how you did document your current procedure (i.e. calibrating once a year)?

Best Regards