Question

Define:

(a) Retention volume.

(b) Corrected retention volume.

(c) Specific retention volume.

Short answer

(a) The volume of mobile phase required to elute a drug from a column is referred to as retention volume.

(b) Corrected retention volumes represent the volume of the mobile phase in the column under real-world chromatography circumstances.

(c) In some literatures, the specific retention volume is defined as the net retention volume per gramme of liquid phase corrected to $273.15K$.

Step-by-step solution

Find Retention volume (part a)

The retention volume refers to the volume of mobile phase (gas) present in the column during the evaluation process - it's the volume required to elute the analyte, and it's stated as:

$V_R=t_R\times F_C$

where $V_R$is retention volume, $T_R$is retention time and $F_C$is flow rate.

Find corrected retention volume (part b)

Corrected retention volume will be expressed with $V_R°$and $V_M°$are expressed by relations:

$V_R°=j\times t_R\times F$

$V_M°=j\times t_M\times F$

where $J$is the correctio factor for pressure drop calculated by the formula :

$j=\frac{3}{2}\frac{\left[{\left(P_i/P\right)}^2-1\right]}{\left[{\left(P_i/P\right)}^3-1\right]}$

Find the specific retention volume (part c)

Specific retention volume, $V_g$is defined by the relation.

$V_g=\frac{V_R°-V_M°}{m_s}\times \frac{273}{T_C}$

where $M_s$is the mass of the stationary phase and $T_C$is the temperature of the column.