Filling a TVIS vial: The relationship between fill height and fill weight

A simple experiment may be used to determine an appropriate amount of liquid to add to a TVIS vial to provide an acceptable value for the fill height within the electrode space. First the vial is weighed empty and then a mass of water is added to over-fill the vial in relation to the height of the electrode. In the case of a 10R vial with an electrode (10 mm in height) placed at a height of 3 mm from the base, a mass of 5 g would be sufficient to over-fill the electrode height. The vial is then placed on a stage with a digital SLR camera positioned in front, and photographs are then taken after removing a aliquot of 0.2 mL (0.2 g) of water, using a pipette. Each photograph is then analysed for the height of the base of the meniscus above the bottom edge of the electrode and a graph plotted of fill height vs weight/volume of water (see attached Excel sheet). In the example shown, a fill height of ~7 mm was chosen, which corresponds to a fill volume of 3.2 mL (3.2 g).