Malvern Instruments has introduced a new, improved disposable folded capillary cell for use in its Zetasizer Nano particle and molecular characterization systems. The new cell is designed to further enhance the reproducibility of zeta potential measurements. It replaces the previous model of folded capillary cell while providing the same ‘plug and play’ convenience for easy application and disposal. Although intended primarily for the measurement of zeta potential, the disposable folded capillary cell can also be used for size measurements and is fundamental to Malvern’s patented diffusion barrier technique for the reliable, high-sensitivity measurement of the electrophoretic mobility (or zeta potential) of labile biological molecules, such as proteins in solution.

Conventionally, a long linear capillary cell is used when measuring zeta potential in order to separate the measurement zone from the electrodes and to provide a sufficiently long surface for the development of a smooth electro-osmotic profile. Malvern’s folded capillary cell has all the advantages of a linear capillary cell while being completely disposable, for applications where there might otherwise be a risk of cross-contamination.

The folded capillary cell is also used in the diffusion barrier technique for measuring zeta potential, where sample is separated from the electrodes in order to avoid aggregation under the influence of the applied electric field. This is done by filling the cell with buffer, then introducing a small volume of sample into the measurement zone. In addition, the ability to measure size in the same cell before and after a zeta potential measurement enables checks to be made that ensure zeta potential measurement has not been affected by any aggregation of the sample.

The Malvern Zetasizer Nano range provides both exceptionally high performance and entry level systems that incorporate combinations of a particle size analyzer, zeta potential analyzer, molecular weight analyzer, protein mobility and microrheology measurements. Particles and molecules from less than a nanometer in size to several microns can be analyzed by a range of variants to suit different applications and budgets.