You did not get an answer? could you find out what does it mean?

Hi Ahmed

if the intercept is negative, the calibration curve must be repeated

because you should have y value zero minimum at zero X value

y value could be increased as the solvent have contamination

don't try to force the line to zero value

another thing

make a trend line it is more accrue, because it is seeming to me the intercept will be positive not negative