Refractometers measure the angle at which light is bent when traveling through a transparent fluid. This measurement is converted to the index of refraction, which is a useful, and relatively simple, analytical method to help identify an unknown substance or determine the concentration of a compound in solution. Refractometers can be benchtop or handheld instruments. They can also be purchased with different scales for various common applications. For a list of laboratory refractometer manufacturers, see our online directory: LabManager.com/refractometer-manufacturers
5 Questions to Ask When Buying a Refractometer:
- Do you need a benchtop or handheld instrument?
- What scale is needed—salinity, brix (sucrose), coolant (glycol), clinical (urine), or specific gravity?
- Is analog or digital the best option for your lab?
- What refractive range is important?
- What accuracy and precision are required?
To get the needed accuracy from the refractometer, samples must be loaded with care. Download this infographic to learn about the best syringes to use, how to avoid air cushions, and how to fill sample holders when using the refractometer: LabManager.com/refractometer-tips-infographic
While refractometers are relatively simple instruments, they still require calibration for accurate results. While many refractometers are calibrated only with a zero reference point, improved performance can be gained by adding a top end calibration point, too. This will help maintain accuracy throughout the measurement range. Traceable standards for calibration are available from the National Institute of Standards and Technology (NIST) and are normally required for regulated work.