What Is A Refractometer?

A refractometer such as brix refractometer or salinity refractometer is a laboratory device used to measure the index of refraction of light as it passes through a solution. This measurement allows the concentration of a solution to be calculated; also, any foreign substances can be identified.

Types

Refractometers come in four primary types, including the traditional and digital handheld models, as well as the Abbe and inline units. Abbe models have the most precision, and are typically used in laboratory and medical environments and resemble a microscope. Inline refractometers are often used in industrial applications to take readings on fluids that are traveling though pipes. Handheld models are generally used by consumers, and the digital type is slightly more precise than a traditional unit. Handheld models are commonly used to measure a number of different solutions–including the amount of sugar present in blood and the salinity of water.

Calibration

All refractometers need to be calibrated before use to ensure an accurate reading. Place one drop of distilled water on the main prism and allow it to sit for 30 seconds to adjust to the ambient temperature of the refraktometer. Close the cover and adjust the calibration dial until the shadow lines up with the zero mark. Open the cover and dry the main prism using a soft cotton cloth.

Operation

Place a drop of the sample you intend to measure onto the main prism and close the cover. A single drop is all that is needed to obtain a reading but be certain that the drop is fresh. Readings must be performed quickly to avoid evaporation, which can distort the results. Look through the eyepiece and adjust the light so the line between the dark and light area is in focus. Once this line is aligned with the scale, record the reading and make note of the temperature as well. Readings should be measured to the nearest 0.1 percent. If you are using a digital refractometer, there will be no eyepiece or manual adjustments required.

If you are taking multiple measurements, dry the refractometer after each measurement with a soft cotton cloth. After every 10 to 15 measurements, use an alcohol solvent to clean and dry the prism. Always store the refractometer in its original case when not in use.

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