A refractometer is a tool that can determine the concentration of a particular substance in a liquid solution. It uses the principle of refraction, which describes how light bends as it crosses the boundary between one medium and another.
A classic way to illustrate refraction is to look at how a pencil that's half-submerged in a glass of water appears bent or discontinuous at the boundary line between one medium (air) and the other (water), because of how the light is refracted.
By measuring how much refraction a solution causes, you can learn about its density, which in turn can give you valuable information about how much of a substance is dissolved in solution.
The most common refractometers are handheld, analog instruments. The sample is placed on a cover plate and a prism and then held to the light to view the scale inside the meter. The readout scale is usually calibrated for determining the concentration of one particular substance.
Here are some common types of refractometer readouts:
To take a measurement with a handheld analog refractometer, follow these steps and read the manufacturer's instructions:
Digital refractometers require a drop of the tested solution to be placed in a well. That well is illuminated by a light source, usually an LED light, and the meter interprets the light transmission into refractive index or whatever unit of measure the instrument is programmed to read.
Abbe refractometers, also called laboratory refractometers, are larger bench-top instruments that provide highly precise measurements of refractive index in lab settings.
Q: I need to test the concentration of lubricating oil but I have a Brix refractometer. Can I use it?
A: Yes, you can use it if the refractive range is similar. In this case, you need to prepare known samples of the lubricating oil and determine the corresponding Brix values. From this data, a chart can be created to convert from the Brix value to the percent oil value.
Q: How do I maintain a refractometer?
A: Generally, refractometers require very little maintenance. When the measurement is complete, wipe the prism with a soft lens tissue. When the instrument is not in use, keep the cover closed to avoid scratching the prism.
The information contained in this article is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This article is not a substitute for review of current applicable government regulations, industry standards, or other standards specific to your business and/or activities and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.
SIGN UP FOR EMAIL
Get more great content like this sent to your inbox.
THE PRODUCTS YOU NEED,
WHEN YOU NEED THEM