6 Keys to Determining the Right Refractometer for You
Precise measurements require precision instruments. Understanding what you need and what is available are essential.
Refractometers are precise optical instruments that determine the purity of liquids, gels and solids by measuring their refractive index (RI). RI is the speed of light in the substance as compared with the speed of light in a vacuum, which means that RI measurements look at the unique, constant, physical characteristics specific to substances.
Refractometers provide RI and % Brix measurements (and other standard scales) for a broad range of industries including agricultural, flavors, fragrance, chemical, petrochemical, industrial fluids, pharmaceutical, automotive and aviation. A common use of refractometers in the food and beverage industry is to calculate the concentration of dissolved solids in solution or the % Brix.
Finding a refractometer that suits your needs and is right for your lab is easy once you’ve answered the following six criteria. Simply determine the specific requirements of your applications within your industry and within your budget
1) Measurement Range and Accuracy
What level of accuracy does your lab require? The first step in matching the appropriate instrument is to know the range and accuracy demands of the application. The range is in terms of either RI or % Brix based on the types of samples to measure. The accuracy requirement is established by the specifications for your product and the criticality of the concentration measurement. In other words, what is the highest and lowest reading value you expect to encounter? And what is the level of accuracy?
2) Temperature Range and Control
Is control of the sample’s temperature critical for the application? RI varies with temperature, so it’s important to consider the temperature control range of a refractometer. Some samples require measurements at elevated temperatures to match production conditions. But if temperature requirements are less stringent, a less costly model may be appropriate.
3) Sample Type
What type of sample is being measured? Is the sample a liquid? If so, is the liquid sample transparent, translucent or opaque? Is the sample a solid? Select the sample gradient that best matches your sample:
- Gradient I - Transparent: water, solvents, alcohol, beverages
- Gradient II - Translucent: fruit juice, corn syrup, antifreeze
- Gradient III - Opaque: vegetable juice, tomato paste, coffee
- Gradient IV - Solid Samples: film, plastics, glass
4) Refractometer Measuring: Manual or Automatic?
Do you prefer a manual or an automatic instrument? Transmission style (manual) is where a sample is placed between two measurement prisms, and the operator aligns the shadowline to the crosshair target by turning a control knob. Reflection style (automatic) is where the operator places the sample and pushes a Read/Measure button. Manual refractometers are often preferred in educational locations, and both styles are used in research.
5) Prism Material Makes a Big Difference
Reichert offers three different optical prisms. The type of prism chosen for the refractometer should be determined by the rigors of the environment. Glass prisms are the most economical but have limited durability. Sapphire prisms are more durable and four times harder than glass, which means they’re ideally suited for demanding applications and less likely to be damaged. The hardest prism is the YAG (Yttrium Aluminum Garnet) prism, which has an exceptional RI range.
Is start-up time a factor? When selecting a refractometer, ensure the software features meet your needs..
Refractometers offer unparalleled precision when determining the purity of liquids and other substances. Analyzing the six keys above will help ensure you get the right refractometer for your lab. For further assistance and questions about refractometers, including specific models, contact Reichert at www.ReichertAI.com.
About the Author
Charlie Smith is the Sales and Distribution Manager for the Analytical Instrument portfolio at Reichert Technologies. This portfolio consists of a family of laboratory refractometers, hand held refractometers, laboratory density meters, and laboratory polarimeters. Smith has many decades of experience helping customers with their concentration measurement applications.
The Reichert tradition of precision instruments has a proud lineage of innovations that began with the first American made microscope by Charles Spencer in 1838 and the founding of the C. Reichert Optical Company in Vienna in 1876. For the past 150 years, we have created almost every breakthrough in refractometry that has become a standard of the industry. Although our name has changed over the years, our commitment to innovation and quality continues in every product we design and build.
Today, Reichert Analytical Instruments, a division of Reichert Technologies, is the only United States manufacturer that designs, manufactures, sells and services a full line of optical refractometers for a wide range of industries.
Reichert Technologies is part of the Ultra Precision Technologies Division within the Electronic Instruments Group (EIG) of Ametek, Inc. Read more about Ametek Reichert refractometers are built with the highest level of attention and precision to accurately measure the Refractive Index and concentration of liquids, gels and solids. They are accurate, reliable and durable, offering outstanding value and optimum performance. From traditional transmission units like the Abbe Mark III, to the automatic digital r2i300, to the top of the line AR9, Reichert has the right instrument solution.