What is the refractive index and viscosity of FBS and PBS to be used in DLS measurements. Please bear in mind, we dont have refractometer or viscometer in the lab. So, what are the values we should use while measuring the size of the nanoparticles in these solvents in DLS?
With respect, why are you stepping into the laboratory if you do not have the basic tools? You need to get access to an Abbe refractometer. I bought one on eBay for $2.60.... See also:
Uses of an Abbe refractometer http://tinyurl.com/lbp4szy
However, the RI of the continuous phase isn't likely to be much different to that of water (1.33). If you're using a Malvern Zetasizer then there's a helpful calculator in the system for such solutions. You can estimate the viscosity by adding a known standard (e.g. 100 nm latex) and adjusting the viscosity value until the standard reads correctly. Again though the viscosity will not be much different that pure water.
Important question is what are you measuring? All solvents/dispersant phases will need filtering to 0.02 microns.
See figure 2 here:
Article Effect of the Refractive Index of Buffer Solutions in Evanes...
As I'd expect, the change in RI compared to water is negligible. Just use the same values.
Note, this is for the dispersion medium, not the dispersed material. For the more advanced DLS calculations, you need to know about the optical properties of the dispersed material, too.
@AlanFRawle I stepped in because of all the other good stuff they had, and I didn't expect that I'd need the refractive index of fbs... Moreover I thought it wud be available online somewhere but when I started looking for it I found out that it's quite a rare thing. Anyway, thanks for your response. Don't worry I didn't feel offended. :)
@john THANKS, it's a nice paper but it is still missing the one for FBS.
See Table I of this 1912 paper:
http://www.jbc.org/content/11/3/179.full.pdf
The change of RI with increasing serum concentration is negligible compared to the uncertainty in the estimation of the size distribution. i.e., it is unlikely you will get better than 5% uncertainty with an "ideal" sample.
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