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How to Use a Vee Gee Refractometer

Refractometers are instruments that measure the critical angle of total reflection and calculate the refractive index, or RI, from this value. The RI of a substance is dependent on the wavelength of light: It increases with decreasing wavelengths. There are a number of different types of refractometers that Vee Gee offers, such as the Abbe refractometer or a series of digital refractometers. The type of Vee Gee refractometer that you use depends on the sample being tested and whether you're testing the sample in the field or laboratory.

Things You'll Need

Sample

Instructions

Abbe Refractometer
- 1
  Calibrate the device using distilled water. Place water in the prism and look through the eyepiece. Turn the control knob until the shadow line is centered on the scale. The shadow line is a vertical line that crosses the scale. Record the reading on the scale to obtain the refractive index. Place the standards that were supplied with the device, including the bromonaphthalene contact liquid and glass standard, onto the prism of the device. The refractive index for these standards should read 1.6300 and 1.5163, respectively.
- 2
  Place your sample on the prism of the Abbe refractometer. The Abbe refractometer is used to analyze liquids, gases, plastics and film samples.
- 3
  Look into the eyepiece. Turn the control knob until the shadow line is centered on the scale. Look for the vertical line that crosses the scale to obtain the refractive index measurement. Record results.
Digital Refractometer
- 4
  Calibrate the Vee Gee digital refractometer by selecting the "Zero" button on the LCD display. This button automatically calibrates the device.
- 5
  Place one to two drops of your sample on the prism of the digital refractometer. Vee Gee refractometers are designed for portability for field measurements of liquid solids testing.
- 6
  Select the "Read/Enter" button on the LCD display. The reading should automatically display within one second. If the measurement isn't within the target range, the red LED alarm on the LCD display flashes.

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