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So I am tasked with making my countries standards sustainable, wherever possible and trying to address any of the 17 SDGs. I came across a test in a certain material specification code that uses microscope and bromoform of AR or GR grade for measuring glass content in the material. USEPA classifies bromoform as possible human carcinogen and I was wondering if it is just used for its' refractive index properties, we could substitute it with safer materials. I found that correct proportions of glucose or sucrose can give up to 1.4 to 1.45 refractive indices. I was wondering if there was a liquid with 1.6 to 1.7 which could be a substitute to bromoform? Rest physical conditions remain normal as in Temperature is around 27C and material should be transparent and operate in Visible light spectrum etc.

Thanks in advance for all the efforts and help!

Meet Saiya
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If you can make do with a a refractive index of ~1.5, look at immersion oils used for microscopy. Since they are widely used in laboratories without restrictions such as a fume hood, they're likely nontoxic, though consult the chemical safety data sheets (SDS) for the particular ones of interest.

Various companies offer higher nD liquids. For example, Cargille has sets of liquids ranging from 1.3 to 1.8. The SDS for Cargille Refractive Index Liquid Series A, which includes 1.6 nD, states, "IARC (International Agency for Research on Cancer): None of the ingredients are listed." That said, if you have questions on toxicity, contact the manufacturer for more specific information.

DrMoishe Pippik
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