What are the volumes of the Millar small animal Dip-well Cuvettes and why do they vary depending on the catheter I use?

We supply 2 different cuvette models for calibrating the volume of small animal PV catheters, the 910-1048 (11 wells) and the 910-1049 (6 wells).

It is essential that you use the known volumes specific to your Catheter and Cuvette model when performing a Dip-Well Cuvette (Volume) calibration, and not just the generic volume of the well. This is because depending on the electrode spacing of your Catheter, the Absolute Volume being measured within a Dip-Well will vary. 

Catheters with smaller spacing will measure less of the Well than catheters with larger spacing. For example, for the PVR-1035 (3.5mm spacing) and PVR-1045 (4.5mm spacing) when used with the 910-1049 Mouse Cuvette:
Catheter       Well 2 Known Volume
PVR-1035                 11uL
PVR-1045                 14.14uL
Therefore, if you assume the same volume value for both catheters, your Volume Calibration will be incorrect.

Volume card for the 910-1048 can be found here , and 
Volume card for the 910-1049 can be found here

The ADInstruments PV Loop Module for LabChart 7 and higher comes with settings files with the known volumes of each small animal catheter type pre-written in to the Calibration Dialogue. In the below example, the known volumes for the 3mm spacing are shown: