How do I select a suitable flow rate according to the column inner diameter?

The right flow rate is dependent on column dimension. The ’’Van-Deemter equation’’ shows the correlation between column length and flow rate:
H= A+(B/v)+C⋅v
The smaller the H value, the better the separation effieciency of the system: H=L/N H or HETP: height equivalent to a theoretical plate
L: column length
N: number of theoretical plates
v: linear velocity of mobile phase
A: Eddy-diffusion parameter, related to channeling through a non-ideal packing
B: diffusion coefficient of the eluting particles in the longitudinal direction,
resulting in dispersion
C: Resistance to mass transfer coefficient of the analyte between mobile and
stationary phase

The H/v-hyperbolic function (X = v, Y = HETP) has a minimum at the optimal velocity (v),where the height equivalent to a theoretical plate (H) has the smallest value and so the separation efficiency is maximum. The following flow rates are typical guiding values for a 5 µm particle size material: ID 2mm flow 0.15ml/min-0.5ml/min ID 3mm flow 0.6ml/min, ID 4 and 4.6mm flow 0.8ml/min-2.0ml/min, ID 8mm 2.0ml/min-4.0ml/min.

We separate molecules and unite people.

Based in Berlin, KNAUER has been serving the sciences since 1962. We develop and manufacture scientific instruments of superior quality for liquid chromatography systems and components, including:

Analytical HPLC / UHPLC
Preparative HPLC
Fast protein liquid chromatography (FPLC)
Multi-Column Chromatography / SMB

We are an established partner in science. Today and in the future.​​​​​​

Do you need more information?

Please contact us!

Follow us