So the Malvern people are going to show up tomorrow morning to demonstrate their Zetasizer Nano… “Is there anything I should get ready for it?” you ask. Well, not really. We’ll bring along the instrument, a laptop with the latest software, all cables and cuvettes – and a simple standard sample. All that is required is a small section of your lab bench space, about one foot for the instrument and another for the laptop. Some clean water and a waste container may be of use, if we get to measure some of your samples. For proteins, our sensitivity calculator helps with sample concentration requirements.

What about different buffers or unusual mixtures?

Complex-solvent-builder (screen shot created by Ulf Nobbmann)

For unusual materials, check their refractive index with google, yet more important are the refractive index and the viscosity values of the dispersant (=the buffer or solvent that your sample is prepared in). Many typical dispersants (H2O, ethanol, methanol,…) are already integrated into the software, or can be created with the unique solvent builder for aqueous buffers. To access the complex solvent builder in the software, access the dispersant within the SOP or manual setup, click on the … next to the default to select a new one, the Add – Complex Solvent and a new window, the complex solvent builder pops up. Within this window create the recipe of your buffer in the respective molarities and click Add for each component. Many common as well as less common components are available in the menu, such as: ethanol, TRIS, propylene glycol, glucose, glycerol, acetic acid, mannitol, methanol, sucrose, ammonia, citric acid, EDTA,… When done with the “recipe”, create a name for your buffer and click OK. The new dispersant is now available, and the software automatically calculates refractive index, viscosity and dielectric constant at any temperature. {As an aside, it is also possible to re-analyze data afterwards if the correct viscosity is not known}

The ideal minimum volume for size measurements is 40 microLiters – which allows the use disposable cuvettes . We can do 12 microLiters in the special quartz cuvette, that requires in between runs.

For zeta potential a volume of 700 microLiters (unique reusable and disposable capillary cuvette, or the dip cell) is required (unless we bring the special high concentration and low volume zeta cell, where about 50uL suffices; it is alos possible to use the diffusion barrier method with only ~20μL of volume).

You want to be extra-prepared?
OK, then arrange for a computer in the lab as backup, any recent (=within the last 3 years) PC/laptop with WinXP/WinVista/Win7 operating system and one available USB port should work. In order to install the software, local administrator access is required. It would be ideal if you or your IT department could already  download and install the software, only a short, free registration with an email address is required. Having the software readily installed provides you with the extra benefit of access to the data in your lab, after we have left.

Looking forward to the visit with you!