Mechanical & Physical

Refractometer

Refractive index and Brix of liquids

A refractometer measures how strongly a sample bends light — its refractive index. It is a fast, small-volume check of identity, purity and concentration for oils, solvents, syrups and solutions.

1 test optionRI range ~1.30–1.70A few drops per readingTypical turnaround 2–4 working days
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Refractometer measurement principleIllustrative
Light sourcePrismSampleTemperature controlDetector arrayReflected intensity
One critical angle, one indexIllustrative
01 / Overview

What is Refractometer?

A refractometer finds the critical angle at which light is totally reflected where a high-index prism meets the sample. The light–dark edge this creates, seen in an eyepiece or on a detector array, gives the refractive index, usually quoted at the sodium D line (589 nm) and 20 °C.

Because refractive index depends on composition and temperature, a temperature-controlled reading is a quick way to identify liquids, check purity and follow concentration, for example as °Brix for sugar solutions. It needs only a few drops and no reagents, but it gives one number, not a chemical breakdown.

02 / How it works

How it works

  1. 01

    Drop is applied

    A few drops of sample are spread over the clean measuring prism.

  2. 02

    Temperature settles

    The prism holds the sample at 20 °C, or as requested, until the reading is stable.

  3. 03

    Light meets the boundary

    Light strikes the prism–sample boundary; beyond the critical angle it is totally reflected.

  4. 04

    Edge gives the index

    The position of the light–dark edge is converted to refractive index or °Brix.

03 / What it measures

What it measures

Refractive index (nD)

Index at the sodium D line, measured at a controlled temperature.

Useful forIdentity and purity of oils, solvents, monomers

Brix / sugar content

Dissolved sugar as °Brix, read from the index of the solution.

Useful forSyrups, juices, fermentation media

Solution concentration

Follow concentration with a calibration of index against composition.

Useful forGlycols, salt solutions, binary mixtures

Temperature dependence

Index at several set temperatures, to see how it drifts with heat.

Useful forOptical fluids, process specifications

Batch consistency

Compare a batch against its specification or a reference sample.

Useful forIncoming material and batch quality control
04 / Test options

Choose the Refractometer options you need

1 option · none added yet

Refractometer test options
05 / Sample requirements

Sample requirements

Accepted forms
Clear or lightly coloured liquids, oils, syrups and solutions
Quantity
About 5 mL per sample; only a few drops are used per reading
Container
Sealed, leak-proof glass or plastic vial, clearly labelled
Solids and films
Flat, polished pieces only after discussing first
Temperature
State the measurement temperature if not 20 °C
  • Homogeneous, well mixed and free of air bubbles
  • Filter out suspended particles or sediment
  • Seal tightly so volatile components cannot evaporate
  • No hydrofluoric acid or strongly corrosive liquids
  • No opaque slurries or pastes without discussing first

Hazardous or air-sensitive samples: mention it in your request, and attach the MSDS if you have one.

06 / Results & turnaround

Results & turnaround

What you receive

  • Refractive index (nD) per sample
  • °Brix for sugar solutions, if requested
  • Measurement temperature and wavelength
  • Mean of repeat readings
  • Report PDF

Turnaround & pricing

Typically 2–4 working days after samples reach the lab.

Price confirmed in your quotation, depending on user type, options and number of samples.

Sample report · IllustrativeExample nD at 20 °C1.4735Illustrative — not measured sample data
07 / Limitations

When Refractometer isn't the right fit

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