Refractometry-Principle-Calibration-Applications-PPT
- Principle of Refractometry. The main principle involved in refractometry is that the refraction supported the speed of the sunshine that passes within the different mediums.
- Determination of refractive index in Refractometry. ...
- Procedure for Determination of refractive index. ...
- APPLICATIONS of Refractometry. ...
What is a refractometer and how does it work?
Refractometer is an optical device that can be used to measure the refractive index of a substance (usually fluid) and, by converting the refractive index, one can get the specific gravity, sugar content (Brix, or Plato).
What is the principle of refractive index of refractometer?
The refractometer works using the principle of light refraction through liquids. As light passes from air into a liquid it slows down. Click to see full answer. Besides, what is the principle of refractive index?
How do you adjust the temperature on a refractometer?
Some refractometers have automatic temperature correction (ATC), a feature that allows the instrument to automatically correct for temperature differences. Place a small amount of liquid (usually 2–5 drops) on the prism and secure the cover plate. This will evenly distribute the liquid on the prism.
What is a specific gravity refractometer?
Used in the food and beverage industry for quality control Specific Gravity: Measures density of a liquid in relation to the density of water, which has a specific gravity of 1. Calibrate the refractometer with a standard solution before use.
What is the principle of Abbes refractometer?
The measuring principle of an Abbe refractometer is based on the principle of total reflection. Abbe refractometers are used for measuring liquids. The reference media glasses (prisms) can be selected with high refractive indices. The light from a radiation source is reflected by a mirror and hits a double prism.
What is the principle of refractometer in determining sugar concentration?
Refractometers are based on the principle that as the density of a substance increases (eg when sugar is dissolved in water) its refractive index rises proportionately. Refractometers utilise a prism which possesses a much greater refractive index than the sample solution to be measured.
What is a refractometer simple definition?
A refractometer is a simple instrument used for measuring concentrations of aqueous solutions. It requires only a few drops of liquid, and is used throughout the food, agricultural, chemical, and manufacturing industries.
How do you use a refractometer to measure concentration?
1:363:24How to use a refractometer to measure coolant concentrationYouTubeStart of suggested clipEnd of suggested clipAt a source of light focus the eyepiece until the brick scale is as clear as possible. Then you readMoreAt a source of light focus the eyepiece until the brick scale is as clear as possible. Then you read the value at the point where the darker half meets the lighter half this is your bricks.
How does a refractometer work salinity?
Salinity can be conveniently measured in a ballast water tank using a refractometer. The instrument works on the critical angle principle, utilizing lenses and prisms to project a shadow line onto a small glass reticle inside the refractometer, which is then viewed by the inspector through a magnifying eyepiece.
What is the important use of refractometer?
A refractometer is most often used to determine the characteristics of a liquid sample. By calculating the refractive index, a researcher may be able to identify a liquid sample, assess the sample's purity, and determine the concentration of solute (that is, dissolved materials) in a liquid solution.
What is the purpose application of the refractometer?
Refractometers are mostly used to determine the index of refraction of liquid samples, and to measure fluid concentrations, such as blood protein concentration, sugar content, and salinity.
Why is refractometry important?
Refractometers are used in a variety of applications: From the determination of the purity and concentration of ingredients of medications to the measurement of the sugar content of food and beverages and the analysis of petroleum oil.
What is a refractometer?
A refractometer is a simple instrument used for measuring concentrations of aqueous solutions. It requires only a few drops of liquid, and is used throughout the food, agricultural, chemical, and manufacturing industries.
How does a refractometer work?
How a Refractometer Works. When light enters a liquid it changes direction; this is called refraction. Refractometers measure the degree to which the light changes direction, called the angle of refraction. A refractometer takes the refraction angles and correlates them to refractive index (nD) values that have been established.
Which has a greater refractive index: solution or prism?
For example, solutions have different refractive indexes depending on their concentration in water. The prism in the refractometer has a greater refractive index than the solution. Measurements are read at the point where the prism and solution meet.
What is a refractometer?
A refractometer is a laboratory or field device for the measurement of an index of refraction ( refractometry ). The index of refraction is calculated from the observed refraction angle using Snell's law. For mixtures, the index of refraction then allows to determine the concentration using mixing rules such as the Gladstone–Dale relation and Lorentz–Lorenz equation .
How does a refractometer work?
Standard refractometers measure the extent of light refraction (as part of a refractive index) of transparent substances in either a liquid or solid-state; this is then used in order to identify a liquid sample, analyze the sample's purity, and determine the amount or concentration of dissolved substances within the sample. As light passes through the liquid from the air it will slow down and create a ‘bending’ illusion, the severity of the ‘bend’ will depend on the amount of substance dissolved in the liquid. For example, the amount of sugar in a glass of water.
How does temperature affect refractive index?
Temperature has a very important influence on the refractive index measurement. Therefore, the temperature of the prism and the temperature of the sample have to be controlled with high precision. There are several subtly-different designs for controlling the temperature; but there are some key factors common to all, such as high-precision temperature sensors and Peltier devices to control the temperature of the sample and the prism. The temperature control of these devices should be designed so that the variation in sample temperature is small enough that it will not cause a detectable refractive-index change.
What is a gemstone refractometer?
In gemology, the gemstone refractometer is one of the fundamental pieces of equipment used in a gemological laboratory. Gemstones are transparent minerals and can therefore be examined using optical methods.
How does an interference filter work?
An interference filter guarantees the specified wavelength. Due to focusing light to a spot at the prism surface , a wide range of different angles is covered.
What are the different types of refractometers?
Types of refractometers. There are four main types of refractometers: traditional handheld refractometers, digital handheld refractometers, laboratory or Abbe refractometers (named for the instrument's inventor and based on Ernst Abbe's original design of the 'critical angle') and inline process refractometers.
What happens when light passes through a liquid?
As light passes through the liquid from the air it will slow down and create a ‘bending’ illusion, the severity of the ‘bend’ will depend on the amount of substance dissolved in the liquid. For example, the amount of sugar in a glass of water.
How does a refractometer work?
The operation of the refractometer is based on the physical principle of light refraction – Snell’s law – which is further described in the next chapter. Light slows down as it passes into more optically dense media, and speeds up as it passes into less optically dense media. The change in speed is accompanied by a change in direction, and at a certain angle of incidence, the light does not refract in the second medium at all , but is entirely reflected. The angle at which this occurs is known as the critical angle, and it is this angle that the refractometer measures.
What is the purpose of refractive index?
Measurement of the refractive index can be used to characterize liquid and solid samples, for example to measure the concentration of solutions. Knowledge of the refractive index allows you to control the quality of multi-component mixtures and check samples for purity. This article will give you a broad overview of this fascinating topic.
What is the refractive index of a substance?
The refractive index of a substance is dependent on the wavelength λ of the light and the temperature T of the substance. Reference to the refractive index must therefore also specify the wavelength and temperature, if the measurement is not done under standard conditions. The standard wavelength for refractometric measurements is 589 nm.
What is the influence of temperature on refractive index?
Temperature is another major influence on refractive index and must therefore be precisely controlled and measured during the entire procedure. While older instruments often employ a water bath for this purpose, newer instruments often have the option to use more precise Peltier temperature control.
Is refractive index relative to air?
While this is the most fundamental definition, it is more common to use the refractive index relative to air. Since the (absolute) refractive index of the medium of interest as well as the refractive index of air depend on temperature, it is necessary to specify the details. Common variants are:
Why is a refractometer important?
A refractometer is used to test the quality of raw materials or finished products.
What is the principle of refractive index?
The Principle of Refractive Index and Refractometer. Refractometer is an optical device that can be used to measure the refractive index of a substance (usually fluid) and , by converting the refractive index, one can get the specific gravity, sugar content (Brix, or Plato). When electromagnetic waves (including visible light) ...
What is the benefit of total reflection?
The advantage of total reflection is that the transmittance of the sample will not influence the measurement too much, when the light doesn't need to pass through the sample. So, to those opaque, high viscosity, or dark samples, the new generation of digital refractometer can still work very well.
What happens when light is reflected from a chopstick?
When the light was reflected from the surface of chopstick and return to the air, the direction of light was changed. So that our eyes saw the 'virtual' image on the straight direction of sight, instead of the original location of the chopstick. In addition, the refractive index (n) of a specific wavelength of light are different.
What is refractive index?
In addition, the refractive index (n) of a specific wavelength of light are different. Today, the standard refractive index, is typically expressed in the unit nD. nD is based on the sodium lamp, which generates a double wavelength light (588.995 nm and 589.592 nm).
What happens when electromagnetic waves pass through the interface of two different substances?
When electromagnetic waves (including visible light) pass through the interface of two different substance, due to its speed changes, it results the direction of light with an angle. This physics phenomenon is known as "Refraction". Typically, in practice, it specifically refers to the refraction of visible light.
Can you find ND in a refractometer?
We can find nD only, in most of the Refractometer instruments today. Besides, in the new refractometer, it has been replaced the old fashion sodium lamp, by a more stable, longer live LED. It makes the instrument more accurate and more stable in the long run. Another factor that affects the refractive index ...
Overview
Types of refractometers
There are four main types of refractometers: traditional handheld refractometers, digital handheld refractometers, laboratory or Abbe refractometers (named for the instrument's inventor and based on Ernst Abbe's original design of the 'critical angle') and inline process refractometers. There is also the Rayleigh Refractometer used (typically) for measuring the refractive indices of gases.
In laboratory medicine, a refractometer is used to measure the total plasma protein in a blood sa…
Refractometry
Standard refractometers measure the extent of light refraction (as part of a refractive index) of transparent substances in either a liquid or solid-state; this is then used in order to identify a liquid sample, analyze the sample's purity, and determine the amount or concentration of dissolved substances within the sample. As light passes through the liquid from the air it will slow down and create a ‘bending’ illusion, the severity of the ‘bend’ will depend on the amount of substance diss…
Automatic refractometers
Automatic refractometers automatically measure the refractive index of a sample. The automatic measurement of the refractive index of the sample is based on the determination of the critical angle of total reflection. A light source, usually a long-life LED, is focused onto a prism surface via a lens system. An interference filter guarantees the specified wavelength. Due to foc…
Scales typically used
• Brix
• Oechsle scale
• Plato scale
• Baumé scale
See also
• Ernst Abbe
• Refractive index
• Gemology
• Must weight
• Winemaking
Further reading
• Sella, Andrea (November 2008). "Abbé's refractometer". Chemistry World: 67.
External links
• Refractometer – Gemstone Buzz uses, procedure & limitations.
• Rayleigh Refractometer: Operational Principles
• Refractometers and refractometry explains how refractometers work.