Refractometers Introduction / Handheld Re Tech Insights How a Refractometer Works The % Brix Scale shows the concentration KEY INFORMATION percentage of the soluble solids content A refractometer is a simple instrument used for measuring concentrations of of a sample (water solution). The soluble aqueous solutions. It requires only a few drops of liquid, and is used throughout solids content is the total of all the solids the food, agricultural, chemical, and manufacturing industries. dissolved in the water, beginning with When light enters a liquid it changes direction; this is called refraction. Refractometers sugar, salts, protein, acids, etc.; the measure the degree to which the light changes direction, called the angle of refraction. measurement reading value is the value of A refractometer takes the refraction angles and correlates them to refractive index the sum total of those. The Brix scale is (nD) values that have been established. Using these values, you can determine the calibrated to the number of grams of cane concentrations of solutions. For example, solutions have different refractive indexes sugar contained in 100 g of water. When depending on their concentration. measuring a sugar solution, the % Brix reading should perfectly match the The prism in the refractometer has a greater refractive index than the solution. actual concentration. Measurements are read at the point where the prism and solution meet. With a low concentration solution, Sample fluid % Brix the refractive index of the prism Cutting oils 0 to 8 is much greater than that of Oranges 4 to 13 the sample, creating a large Carbonated beverages 5 to 15 refraction angle and a low Apples 11 to 18 reading (“A” on diagram). The Grapes and wines 14 to 19 reverse would happen with a Concentrated juices 42 to 68 high concentration solution (“B” Condensed milk 52 to 68 on diagram). Jams and jellies 60 to 70 Common Refractive Indexes: Refractive index readings are temperature-dependent. Refractive Sample fluid Temperature index Methanol 25°C 1.326 Acetone 25°C 1.357 Ethanol 25°C 1.359 Acetic acid 25°C 1.370 Benzene 25°C 1.498 Paraffin oil 20°C 1.412 TW-17105-00 NIST-traceable calibration Palm oil 20°C 1.456 with data for refractometers Olive oil 20°C 1.471 Methyl salicylate 25°C 1.522 Methyl iodide 25°C 1.740 Low-Cost Brix and Salt Refractometers Durable units provide quick and easy measurements Use these economical refractometers to take quick and easy measurements. Refractometers feature adjustable focus and a zero adjustment screw for calibration. 32 Each refractometer is calibrated and adjusted to read at 68°F (20°C). Models with 30 81150-06 automatic temperature compensation (ATC) are ideal for applications where the * * temperatures of your samples vary. * Refractometers are made of corrosion-resistant brass and have rubber-insulated grips. 4 Include hard case, calibration screwdriver, and instructions. 2 0 Brix Refractometers measure soluble solid concentration of sugars, salts, proteins, and more in foods and liquids—ideal for quality control and R & D applications. Use to measure percent Brix of juices, beverages, and other sugar-based liquids. Salt Refractometers measure salt content in parts per thousand (ppt) and specific gravity or percent salinity, depending on model. Use to measure salt concentration of water or brine. Catalog number Range Resolution Accuracy ATC Price Brix refractometers TW-81150-02 0 to 10% Brix 0.1% Brix ±0.1% Brix 50 to 86°F (10 to 30°C) 1.070 100 TW-81150-04 0 to 18% Brix 0.2% Brix ±0.15% Brix No 1.060 90 TW-81150-06 0 to 32% Brix 0.2% Brix ±0.2% Brix No * * TW-81150-08 0 to 32% Brix 0.2% Brix ±0.2% Brix 50 to 86°F (10 to 30°C) * * TW-81150-10 28 to 62% Brix 0.2% Brix ±0.2% Brix No * * TW-81150-12 45 to 82% Brix 0.5% Brix ±0.3% Brix No 1.020 20 TW-81150-14 58 to 90% Brix 1.0% Brix ±0.5% Brix No 81150-20 1.010 10 Salt refractometers 1.000 0 0 to 100 ppt salinity; 1.0 ppt; ±1.0 ppt; TW-81150-20 50 to 86°F (10 to 30°C) 1.000 to 1.070 SGU† 0.001 SGU† ±0.001 SGU† TW-81150-22 0 to 28% salinity 0.2% ±0.2% No †SGU = specific gravity units TW-17105-00 NIST-traceable calibration with data for refractometers US Toll-free: 800-323-4340 • Outside the US: 1-847-549-7600 • www.coleparmer.com 1469 Canada 800-363-5900 • India 91-22-6716-2222 • UK 0500-345-300.