Issue-06 (06/2004)
Rings are for Fingers - Plates are for Surface Tension
This note explains some of the pitfalls of using ring tensiometry on surfactant solutions, without understanding the dynamics of ring situation, relative to the dynamics of surfaces. It answers, in some detail, the classic question of "When do I use a ring and when do I use a plate?", and gives a prelude to another note in this issue on non-equilibrium tensiometry.
Delta-8 -
surface tension measurement in modern industrial R&D
Delta-8 is the very first 8-channel analyzer designed for fully automated high throughput measurement of surface tension of liquids. This novel instrument employs disposable cuvettes (of the standard 96-well format). The small sample volume of 50 microliters/well makes the instrument particularly well suited for applications where material availability is limited as is often the case in pharmaceutical and surfactant R&D. The measurement itself is based on the maximum pull force, yet using a small diameter wire probe (0.5 mm) instead of a du Nouy ring. The instrument is equipped with electric probe cleaning and can thus be easily integrated with robotic liquid handling systems, thus significantly reducing the need for instrument attendance and manual laboratory work.