brother the best way is Refractometer device is very simple in use and very accurate but you should choose it according to wavelength.

Thank you for you message. Unfortunately, I don't have access to Refractometer at the moment. I did mean theoretical calculation for refractive index of the solution at various concentration.

Just a hint - Clausius-Mozotti equation might lead to desired solution. But you will need polarizabilities of ions and molecules - you have to find them out either in handbooks or calculate e.g. using quantum chemistry software. I am not aware of other ways to calculate refractive index of media given its composition, will be glad to learn another ways.

Or you might be lucky to find results published somewhere. For example, such data is available for solutions of several salts which I use in my work. Normally, the dependence of refractive index on concentration is practically linear so you need data only for one concentration.

Hi Nasih;

Look at this article if you don't have access to refractometer:

Refractive index of dye solution

Applied Optics, Vol. 28, Issue 20, pp. 4268-4269 (1989)

http://dx.doi.org/10.1364/AO.28.004268

in a first approximation you may use proportional rules to estimate the RI of the mixture:

RI of AgNO3 is xxx

RI of water is ~1,333

so much AgNO3 in water makes a proportion of RI of AgNO3 and a proportion of RI of water

I doubt that there will be any significant change of RI when you use such low concentrations. The imaginary part may change significantly if silver ions strongly absorb, but if your solution still looks fully transparent, I'd use the RI of pure water without corrections. What do you need the RI for? Would changes of the second digit after the decimal point at all matter?

Hi, Roman,

The question in marked as SPR topic, where RI resolution of a typical instrument is in the 10^-5 / 10-^6 range (down to 10^-7 and more with advanced setups). But you are still right with your concerns - with so small concentrations (less than 1 mM? maybe mg/ml were actually meant?) I doubt that the difference in refractive indices will be easily measurable.

Nasih, Did you get any answer you are looking for? I am also looking for refractive index (theoretical method or some published data ) of elemental solution ( like, Pb, Mg, Cd in 2% nitric acid, 1000 ppm ) . Can you help me?

Hello everybody! I'm wondering if the would be any way to calculate refractive index of solutions. I'm also working on SPR and I am searching a way of calculation. Till now all I could do is a mathematical model according to the litterature's results.

Not of direct help to the question asked, but I offer:

Langford, S. A., and J. K. Nakagawa, 1978. A general equation for estimating refractive indices of Cargille liquids at various temperatures and wavelengths. The Microscope, v. 26, no. 4, pp. 167 - 170.

&

Langford, S. A., 1991. A modified Jelley refractometer. The Royal Microscopical Society J. Microscopy, v. 163, pt. 3, September, pp. 333 - 345. [Please note that the equation on p. 339 requires addition of constant 1.517207, which was inadvertently lost due to an interruption during my final editing work. The correction was published in a later issue, which I can not locate on the Web. --SL, 20 Oct 2016] https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2818.1991.tb03184.x, tinyurl.com/ya9ahlc8.

For purposes of liquid-immersion refractometry [see, for instance, < https://tinyurl.com/yabku63f >] I think that there is no substitute for calibration of liquids soon before they are to be used. Better yet would be the development of an instrument that would continuously log Liquid RIs during liquid-immersion work.

I hope that these thoughts help at least some readers. :-)

-Steve-