We are trying to measure nanoparticles composed of dextran polymers using Zetasizer ZS (Malvern). The system requires Refractive Index (RI) of material we use for nanoparticle production. Hence, we are trying to find a method to measure the RI of two dextrans with molecular weight of 40 and 70kDa. Thank you all for answers!
This NIST (or NBS as it was when published) paper is excellent by the way:
http://nvlpubs.nist.gov/nistpubs/jres/53/jresv53n3p131_A1b.pdf
Within this paper there's an RI for 0 and 1% dextran solutions (Table 12). We can use this table to estimate the RI of pure dextran. RI water @ 20 C = 1.33299; RI of 1% dextran = 1.33451. Difference = 1.33451 - 1.33299 = 0.00152. Extrapolating to 100% dextran gives an increment of 0.152. Thus an estimate of the RI is 1.33 + 0.15 = 1.48. We've found this extrapolation works well where there is little interaction between material and solvent. See for example (slides 44 onwards) in: Note that these will now (2019) only open in Internet Explorer due to Flash player issues:
Sept 21st, 2006 Optical Properties - Becke Lines, Immersion Fluids
http://www.brainshark.com/brainshark/vu/view.asp?pi=577723565&text=M021507
Also, for example:
June 3rd, 2014 Optical properties of organic materials
https://www.brainshark.com/malvern/vu?pi=393555978
Jun 27th, 2006 Optical Properties - use and abuse
http://tinyurl.com/jo2u6p9
Jan 24th, 2006. Optical Properties: the Gladstone-Dale approach
http://www.brainshark.com/brainshark/vu/view.asp?pi=141109&text=M021507
Hell Michal If you're measuring the intensity distribution, then you do not need the optical properties for DLS size measurement. Ulf Nobbmann has posted some excellent posts on ResearchGate and Materials Talks on this matter. Se for example:
http://www.materials-talks.com/blog/2014/08/05/faq-how-important-are-refractive-index-absorption-for-nanoparticles/
http://www.malvern.com/en/pdf/secure/TN101104IntensityVolumeNumber.pdf
If your material is pure and close to monodisperse then the intensity mean will be close to the volume mean. Number results should never be used for specification purposes from DLS.
Incidentally there is a calculator in the Malvern software that allows you to estimate the size from the MW and shape and thus check your results. I attach 40 and 70 kDa calculations
This NIST (or NBS as it was when published) paper is excellent by the way:
http://nvlpubs.nist.gov/nistpubs/jres/53/jresv53n3p131_A1b.pdf
Within this paper there's an RI for 0 and 1% dextran solutions (Table 12). We can use this table to estimate the RI of pure dextran. RI water @ 20 C = 1.33299; RI of 1% dextran = 1.33451. Difference = 1.33451 - 1.33299 = 0.00152. Extrapolating to 100% dextran gives an increment of 0.152. Thus an estimate of the RI is 1.33 + 0.15 = 1.48. We've found this extrapolation works well where there is little interaction between material and solvent. See for example (slides 44 onwards) in: Note that these will now (2019) only open in Internet Explorer due to Flash player issues:
Sept 21st, 2006 Optical Properties - Becke Lines, Immersion Fluids
http://www.brainshark.com/brainshark/vu/view.asp?pi=577723565&text=M021507
Also, for example:
June 3rd, 2014 Optical properties of organic materials
https://www.brainshark.com/malvern/vu?pi=393555978
Jun 27th, 2006 Optical Properties - use and abuse
http://tinyurl.com/jo2u6p9
Jan 24th, 2006. Optical Properties: the Gladstone-Dale approach
http://www.brainshark.com/brainshark/vu/view.asp?pi=141109&text=M021507
Please look at our paper devoted clinical dextran (aqueous solution of 0.9 NaCl)
https://www.researchgate.net/publication/236194271_Refractive_and_chiroptical_properties_of_clinical_dextrans_Pol_J_Env_Studies_15_66_2006
Article Refractive and chiroptical properties of clinical dextrans.
I notice that dispersion of n was measured also for low MW dextran. So please seethe paper below
https://www.researchgate.net/publication/260213899_Magnetic_properties_of_ferritin_and_akaganeite_nanoparticles_in_aqueous_suspension?ev=prf_pub
Article Magnetic properties of ferritin and akaganeite nanoparticles...
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