Precise Dosing for Fully Automatic CMC Measurements

At analytica 2014, Krüss GmbH (Germany) will present the Micro Dispenser, a dosing unit for fully automatic measurements of the critical Micelle concentration (CMC). The Hamburg-based manufacturer of measuring instruments has developed the Micro Dispenser especially for the Force Tensiometer K100, which has taken up an established position in the market for some time now. Two combined Micro Dispenser units create the whole concentration series for the surfactant to be analysed directly inside the measuring vessel of the tensiometer. The K100 measures the surface tension between the respective dosing steps fully automatic by using the ring, plate or rod method.

By software-controlled dosing and subsequent removing the added volume between measurements, a vast number of concentrations can be analysed without being limited by the vessel size. Thus, a dilution by several orders of magnitude can be achieved in order to cover the concentration range of the CMC reliably. Since the concentration steps can also be chosen very close to one another, the CMC can be determined based on a large number of measurements and thereby with high precision. The very accurate dosing volume of the Micro Dispenser minimises the systematic measurement error even for very large concentration series. This also contributes to the precision of the system.