What is the working principle of Abbe refractometer?
The Abbe refractometer, named after its inventor Ernst Abbe (1840-1905), was the first laboratory instrument for the precise determination of the refractive index of liquids. The measuring principle of an Abbe refractometer is based on the principle of total reflection.
Why do we use a compensator in an Abbe refractometer?
The compensator (rotating prism) corrects for the dispersion inherent in the refractometer optics and the sample when using white light. The compensator is adjusted using the large dial on the front of the instrument.
How will you read the results using the refractometer?
Point the front of the refractometer again toward a light source and look into the eyepiece. You will now see the line delineated at a different point on the refractometer’s internal index. Read the point on the index at which the line falls to determine the refractive index of your liquid sample.
How do you calibrate an Abbe refractometer?
Lift the daylight plate and place 2 to 3 drops of the calibration liquid on the prism assembly. Close the daylight plate and allow the calibration liquid to spread across the prism without any dry spots. Wait 30 seconds so the sample can reach the temperature of the refractometer.
What prisms are present in the Abbe refractometer?
In the Abbe refractometer the liquid sample is sandwiched into a thin layer between an illuminating prism and a refracting prism.
Why the source of light in refractometer should be monochromatic?
The refractive index varies with wavelength linearly because different wavelengths interfere to different extents with the atoms of the medium. It is important to use monochromatic light to prevent dispersion of light into different colours. The chosen wavelength should not be absorbed by the medium.
What is the accuracy uncertainty of the refractometer?
* Refractometers are accurate ±0.2% when used under normal conditions. 2. Note the temperature at the time of readings. Most ATC refrac- tometers operate properly in the 68-86ºF range.
How do you use a Bausch and Lomb refractometer?
Allow the bath to warm up for several minutes before checking the thermometer on the side of the refractometer to verify that the proper temperature has been reached; adjust the temperature of the water bath as needed. Turn on the refractometer (on the back of the Bausch and Lomb, or on the left side of the Fisher).
What is a Refractometer used to measure?
A refractometer is a device for measuring the index of refraction of a liquid sample, which is the ratio of light’s velocity in a vacuum to its velocity in the sample. The index of refraction can be measured very precisely; precisions up to ±0.00003 can be obtained, although most commercially-available instruments have a precision of ±0.0001.
How do I set the temperature of my refractometer?
If desired, turn on the water bath and set it for 20.0 °C. Allow the bath to warm up for several minutes before checking the thermometer on the side of the refractometer to verify that the proper temperature has been reached; adjust the temperature of the water bath as needed.
What solvents and compounds cannot be analyzed on this refractometer?
The following solvents and compounds cannot be analyzed on this refractometer: DMF; phenols, cresols and other tar acids; acetic acid solutions; N, N-dimethylacetamide; THF; mixtures of esters (especially methyl acetate and vinyl acetate); some lacquer thinners; strong mineral acids and bases.