The Refractometer: How to Get Faster Readings

Cole-Parmer Digital Refractometer

Test concentrations of solutions from nectar to the purity of a sample.

Searching for a refractometer? We’re talking refractometers and refraction here. Learn what it is, what it does and we’re giving you a tip on one refractometer that can give you readings without waiting.

What is a refractometer?

A refractometer is an instrument used for measuring concentrations of aqueous solutions. It requires only a few drops of liquid and is used throughout the pharmaceutical, food, agricultural, chemical, and manufacturing industries. A refractometer can be found in a pharmaceutical lab, a winery, a mechanics toolbox and even a gemologist’s desk. Home beer brewers and aquarium keepers also use it. Refractometers can test everything from nectar to the authenticity of emeralds.

How a refractometer works

When light enters a liquid it changes direction; this is called refraction. Refractometers measure the degree to which the light changes direction, called the angle of refraction. A refractometer takes the refraction angles and correlates them to refractive index (nD) values that have been established. Using these values, you can determine the concentrations of solutions. For example, solutions have different refractive indexes depending on their concentration in water.

prism in a refractometer

The prism in the refractometer has a greater refractive index than the solution. Measurements are read at the point where the prism and solution meet. With a low concentration solution, the refractive index of the prism is much greater than that of the sample, creating a large refraction angle and a low reading (“A” on diagram). The reverse would happen with a high concentration solution (“B” on diagram).

Never wait for a reading again

The Cole-Parmer® digital refractometer (shown as the features image) features an LCD, eliminating reading errors with common handheld refractometers. All models feature built-in automatic temperature compensation (ATC) which removes temperature fluctuations allowing the user to concentrate on the measurements. The compensation range is 41 to 104°F (5 to 40°C). Many range options are available for measurements within any application. All models also feature a 0% adjust with distilled water, allowing for immediate and easy calibration for precise measurements at all times.

Learn more. See the Brix scale in the article, What is a Refractometer?

Need Refractive Index Standard Solutions?

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