I need to check the presence (and also purity approx) of a substance in solution. I have a very good reference (10mg/1ml - the substance in water).

Can I use a refractometer to do this?

I am trying to separate the substance from several other ingredients using ether initially then water. At that point, I'd like to see what I have. Is my target in the water? If so can I ballpark the purity?

I was hoping that I could use a refractometer because I have such an excellent reference.

Can I use a standard handheld refractometer from say amazon with say a Brix scale? Or am I way off?

Obviously, there isn't a handheld refractometer I can buy that measures my specific product.

Are refractometers essentially generic? Can I get one with a standard scale and use that to measure the reference and then compare with my extract/filtrate?

  • $\begingroup$ Any solute in water will change the refractive index. If you have a single substance dissolved in water, you can use the refractive index to estimate the concentration. If it is a mixture of unknown ratio of solutes, you need a different method. Also, a handheld refractometer will be fine for high concentrations (sugar in wine, etc), but not for diluted solutions $\endgroup$
    – Karsten
    Nov 20, 2020 at 15:26
  • $\begingroup$ You can derive at most one parameter from one measured variable, not two. $\endgroup$
    – Karl
    Nov 20, 2020 at 17:55
  • $\begingroup$ Short answer is NO. Many are sold for specific application - e.g. determining urine SG (medical diagnostics) or sucrose concentration in liquids (food & beverage industry). They have limited range, one or two targeted algorythms and displays result/values as e.g. SG or deg Brix. You probably want something more versatile, so read some good articles on how to choose a refractometer. $\endgroup$
    – Gwyn
    Nov 20, 2020 at 21:59
  • $\begingroup$ If you know the theory, have a good eye (and steady hand if it's hand-held) and can do the math, get an old-fashioned Abbe type (analog) and you can use it for pretty much anything. $\endgroup$
    – Gwyn
    Nov 20, 2020 at 22:03
  • $\begingroup$ Sounds like chromatography might be helpful. It can be simple (paper), using water or alcohol (not ether - too volatile) to elute), or more elegant: thin film, or even gas chromatography. Develop with iodine in a jar, or maybe you can see a spot with some other reagent. $\endgroup$ Nov 21, 2020 at 16:43


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