Void Volume Calculation for chromatography.

1. Void Volume
Presented By
MD. MORSHEDUL HAQUE
4th year student
Department of Environmental Sciences
Jahangirnagar University, Savar, Dhaka.

2. Definition - What does Void Volume mean?
Void volume is the volume of the pores or space between
particles in:
• Ion exchanger
• Filter media
• Other granular material
This is often expressed as a percentage of the total
volume occupied by the material.
Void volume refers specifically to the volume of the
liquid phase contained inside a column. The same term is
sometimes also used informally to refer to the volume of
a cavity in the column/tubing or fittings.
Void volume is also known as dead volume.

3. Determination of Void Volume
Void volume is the volume of mobile phase (Vm or V0)
in a column. In an ideal case, it is equal to the mobile
phase hold-up volume.
For example, if the stationary phase occupies 40% of the
total column volume, the void volume would be 60% of
the total column volume.
In column chromatography, the volume of the mobile
phase is the total bed volume of the column minus the
volume occupied by the support particles.

4. Calculation of Void Volume
The equation of determination of void volume:
V= 𝜋𝑟2L
Where, V = Column Volume
r = inner diameter
L = length of column
r
L

5. Example
Consider a column that is 25 cm long with an inner
diameter of 1 cm.
V= 𝜋𝑟2L
= 3.14× 0.52 × 25 𝑐𝑚
= 19.6 mL
The total column volume is 19.6 mL.
If the mobile phase occupies 60% of the column
volume
The void volume is 60% of 19.6mL=11.8 mL.

6. Estimation of total Void Volume
Various methods to estimate the total void volume
include:
• Pycnometry
• Minor disturbance method
• Tracer pulse method
• Hold-up volume based on unretained compounds
• Accessible volume based on Martin's rule and its
descendants

7. Reference
• https://www.corrosionpedia.com/definition/1150/voi
d-volume
• VOGEL’S, Textbook of Quantitative Chemical
Analysis, Sixth Edition.

8. Thank You