# Gas Chromatography Detectors - Detector Linearity > Determination of Response Index > The Logarithmic Dilution Method of Linearity Measurement > Page 9

The mass of solute removed (dm) is given by

_{}

where (C_{t}) is the concentration of solute in the
vessel after time (t).

The mass change (dm) will result in a change
in concentration (dC_{t})

_{}

and _{}

Integrating _{}

_{}

where (Q) | is the flow rate, |

(v) | is the volume flow of mobile phase through the system after time (t) |

and (k) | is the integration constant. |