Who can tell me, how I can mesure the Vd in my HPLC system?
I know,it is important to mesure it, but I don't know how?

We do not work with viruses here so I could not tell you how to calculate VD in your HPLC. But, if you mean DV, dwell volume than there is an easy way to approximate it. Inject something that does not retain on the column. Multiply the retention time by the flow rate. Your left with volume.

We do not work with viruses here so I could not tell you how to calculate VD in your HPLC. But, if you mean DV, dwell volume than there is an easy way to approximate it. Inject something that does not retain on the column. Multiply the retention time by the flow rate. You are left with volume.

Assuming you mean the dead volume of a RP
column-the elution volume of uracil will be very
close the the actual dead volumn.

This is to calculate the column dead volume.

If you mean Dwell Volume of the instrument/pump then there is a separate procedure.

Set up your instrument with

Reservoir A - Methanol
Reservoir B - Methanol + 0.1% Acetone
No column connected
UV Detector Wavelength - 260 nm
Flow - 1.0 mL/min
Linear Gradient from 0-100% B in ~20 minutes

Your "Chromatogram" will have a flat baseline for a period, then rise gradually (~linearly) to a flat maximum.

Determine the time when the absorbance is halfway between the original baseline and the maximum. Subtract half the gradient time (here 10 minutes).

The result is the dwell time (or dwell volume / flow rate).

So if the midpoint of the absorbance is at 13.2 min, you get

13.2 - 10.0 = 3.2 minutes
or
3.2 min * 1.0 mL/min = 3.2 mL

(Reference Practical HPLC Method Development, Snyder, Kirkland, Glajch, Second Edition page 392-394)

If your trace is non-linear or shows significant curvature at top and bottom, you might want to check that the gradient equpiment is working properly.

Thank you for your response.
Cordially