Colorimeter – Working Principle, Definition, Parts, Uses

What is a Colorimeter?

Colorimetry is the measurement of the visible part of the electromagnetic spectrum’s wavelength and intensity of electromagnetic radiation. Since the amount and colour of light that is absorbed or transmitted depends on the parameters of the solution, including the concentration of particles in it, colorimetry can be used to determine the concentration of substances. A colorimeter compares the quantity of light passing through a solution to the amount of light passing through a sample of pure solvent. A photocell within a colorimeter may detect the amount of light that passes through the investigated solution. The current produced by a photocell is proportional to the amount of light striking it, thereby demonstrating its absorption of light. A colorimeter takes three wideband readings over the visible spectrum to approximate the colour of a sample. Different pigments absorb light at various wavelengths.

Working Principle of Colorimeter/How does a colorimeter work?

When a light beam with intensity I0 passes through a solution, some of the incident light is reflected (Ir) and absorbed (Ia), while the remainder of the incident light is transmitted (It).

i.e., Io = Ir + Ia + It

The measurement of (I0) in the colorimeter eliminates (Ir) and is adequate for calculating the (Ia). Using cells with identical characteristics keeps the amount of light reflected constant (Ir). After that, (I0) and (It) are measured.

Beer-law Lambert’s states that the amount of light absorbed by a colour solution is directly proportional to the concentration of the solution and the length of the light path through it.

A ∝ cl

A = ∈cl

Where,

• A = Absorbance/ Optical density of the solution
• ∈ = Coefficient of absorption
• c = Concentration of solution
• l = Length of the path     

A colorimeter’s lenses direct a beam of light with a certain wavelength through a solution on its route to the measuring instrument. This examines the colour by comparing it to a current standard. A microprocessor then calculates the absorbance or percent transmittance. It is feasible to determine the concentration of a solution and the amount of light it will absorb by measuring the difference between the amount of light at its source and that after passing through the solution.

Initially, a number of sample solutions with known concentrations are generated and assessed in order to determine the concentration of an unknown sample. Calibration curve is obtained by plotting concentrations against absorbance on a graph. On the curve, the results of the unknown sample are compared to those of the known sample to determine the concentration.

Diagram of Colorimeter

Instrumentation of Colorimeter

1. Light Source: The light source must generate sufficient energy over the entire visible spectrum (380-780nm). Tungsten lamps are commonly used.
2. Slit: It permits a beam of light to pass through and reduces unwanted light.
3. Condensing lens: produce a parallel light beam.
4. Monochromator: It produces monochromatic radiation (one wavelength band) from polychromatic radiation (white light) supplied by a light source. It allows the required wavelength through. It is possible to employ prisms, gelatin fibres, grating monochromators, and interference filters.
5. Sample Holder (Cuvette): The monochromatic light from the filter travels through the cuvette containing the colourful sample solution. Their sizes range from square to rectangular to circular, and their diameter is a constant 1cm. Glass, quartz, and plastic cuvettes are the three varieties based on their respective compositions.
   1. Glass cuvettes are inexpensive and absorb light with a wavelength of 340 nm.
   2. Quartz cuvettes allow both UV and visible light to pass through.
   3. Plastic cuvettes are less expensive, scratch easier, and have shorter lives.
6. Photo detectors: Photodetectors assist in turning the resultant transmitted light rays into an electrical signal once they pass through the sample container. It is also known as a photocell. In colorimeters, numerous types of sensors are utilised based on the material employed. Photocells made of selenium, phototubes, and photocells made of silicon are examples of regularly employed detectors.
   1. Selenium photocell: Selenium photocell is the simplest sort of detector and operates without the need for external power sources.
   2. Phototube: The phototube consists of a glass bulb coated with photosensitive substances such as cesium or potassium.
   3. Silicon photocell: When a photon of light meets the semiconductive surface of the silicon photocell, electrons are produced.
7. Filter: The types of filters vary depending on the manufacturer of the colorimeter. Monochromatic (just one wavelength) or polychromatic (many wavelengths) depending on the wavelength (white light). There are four choices available: gelatin, interference, grating, and prisms.
   1. Gelatin filters: Gelatin filters consist of a small layer of coloured gelatin sandwiched between two thin glass plates. These filters are inexpensive, but they can absorb 30-40% of all incident radiation, reducing the energy throughput of the detectors.
   2. Glass filters: tinted glass filters with wide bandpasses up to 150 nm are another form of filter. By combining several glass filters, specific wavelengths can be attained.
   3. Interference filter: It consists of several semi-transmissive, semi-reflective silver sheets separated by thin layers of transparent dielectric material. Multiple reflections are created between the semitransparent mirrors as white light passes through the dielectric layers. Here, some light ray energy travels directly through the filter. This is the wavelength required for analysis. The thickness of the dielectric layer determines the light’s resulting wavelength.
   4. Grating monochromator: It generates monochromatic light and consists of several parallel grooves closely spaced on a polished surface made of steel, glass, or quartz. A common grating may have 500-600 lines/mm, whereas research-based equipment may have 1200-2 000 lines/mm. When white light strikes the grating, different wavelengths are deflected at different angles.
   5. Prism: It splits white light into its component wavelengths. Selecting the desired spectrum is accomplished by rotating the prism. The colorimeter’s prism is composed of glass and operates within the wavelength range of 350-800 nm.
8. Display: It monitors and measures the electrical signal and produces output that is visible.
9. Measuring device: The current from the detector is supplied to the measuring device, the galvanometer, which displays a metre value that is directly proportional to the light intensity.
10. Control panel: A control panel is used to operate the colorimeter and input the necessary parameters for the measurement. The control panel may include buttons, switches, and other controls.
11. Power source: A power source, such as a battery or AC adapter, is used to power the colorimeter.

Types of Colorimeter

The many varieties of colorimeters are distinguished by the instrument’s size and the filters that it employs. On the basis of size, there are two types of colorimeters: benchtop and portable. Depending on the filters employed, there are three types of colorimeters: tristimulus, densitometer, and spectrophotometer.

Types of Colorimeter Based on size

1. Benchtop colorimeter

1. Workbench colorimeters are slightly larger in size and must be operated on a benchtop. It has a wavelength range of 420-660 nm.
2. It is extremely precise and uses only 1.5 ml of reagent. It is useful for compound analysis in various laboratories.

Advantages of Benchtop colorimeter

Some advantages of using a benchtop colorimeter include:

1. High accuracy: Benchtop colorimeters are designed to be used in a controlled laboratory environment, which allows for higher accuracy in measurement.
2. High precision: Benchtop colorimeters use advanced measurement technologies and have more sophisticated optics, which allows for higher precision in measurement.
3. Wide measurement range: Benchtop colorimeters can measure a wide range of colors and wavelengths, making them suitable for a variety of applications.
4. Large sample capacity: Benchtop colorimeters often have a larger sample capacity than portable/handheld colorimeters, which allows them to measure larger samples or multiple samples at once.
5. Stable measurement: Benchtop colorimeters are more stable than portable/handheld colorimeters, as they are designed to be used on a stationary work surface. This can be important in applications where stability is critical, such as in the production of highly precise or sensitive materials.
6. User-friendly interface: Benchtop colorimeters often have a user-friendly interface, which makes them easy to use and allows for efficient data collection.
7. Customization options: Many benchtop colorimeters can be customized with a variety of measurement accessories and options, which allows them to be tailored to specific applications and needs.

Disadvantages of Benchtop colorimeter

Some disadvantages of using a benchtop colorimeter include:

1. High cost: Benchtop colorimeters are generally more expensive than portable/handheld colorimeters due to their larger size, higher accuracy, and greater precision.
2. Large size and weight: Benchtop colorimeters are larger and heavier than portable/handheld colorimeters, which can make them less convenient to use and transport.
3. Limited portability: Benchtop colorimeters are designed to be used on a stationary work surface, which limits their portability and makes them less suitable for use in field or on-site applications.
4. Limited versatility: Benchtop colorimeters are generally more specialized and less versatile than portable/handheld colorimeters, which may limit their suitability for certain applications.
5. Requirement for a stable work surface: Benchtop colorimeters require a stable work surface to operate accurately, which may not always be possible in certain environments or applications.
6. Limited measurement range: Some benchtop colorimeters may have a limited measurement range, which may not be suitable for certain applications that require a wider range of measurement.
7. Complexity: Some benchtop colorimeters may be more complex and require more training to operate than portable/handheld colorimeters.

2. Portable/handheld colorimeter

• It is a portable/handheld colorimeter that is easily transportable outside of a laboratory setting.
• It can be utilised for food and water analysis in the field. General manufacturers provide a wavelength range of 420-660 nm.

Advantages of Portable/handheld colorimeter

Some advantages of using a portable/handheld colorimeter include:

1. Portability: Portable/handheld colorimeters are small and lightweight, which makes them easy to carry and use in a variety of locations.
2. Versatility: Portable/handheld colorimeters are generally more versatile than benchtop colorimeters, as they can be used in a variety of locations and can be easily carried from one place to another.
3. Convenience: Portable/handheld colorimeters are convenient to use, as they do not require a stationary work surface and can be easily carried in a bag or pocket.
4. Low cost: Portable/handheld colorimeters are generally less expensive than benchtop colorimeters due to their smaller size and less advanced measurement technologies.
5. Easy to use: Portable/handheld colorimeters are generally easy to use, with simple controls and a straightforward design.
6. Long battery life: Portable/handheld colorimeters often have a long battery life, which allows them to be used for extended periods of time without the need for recharging.
7. Suitable for field and on-site applications: Portable/handheld colorimeters are well-suited for field and on-site applications, as they can be easily transported and used in a variety of locations.

Disadvantages of Portable/handheld colorimeter

Some disadvantages of using a portable/handheld colorimeter include:

1. Lower accuracy and precision: Portable/handheld colorimeters are generally less accurate and precise than benchtop colorimeters due to their smaller size and less advanced measurement technologies.
2. Limited measurement range: Some portable/handheld colorimeters may have a limited measurement range, which may not be suitable for certain applications that require a wider range of measurement.
3. Limited sample capacity: Portable/handheld colorimeters often have a smaller sample capacity than benchtop colorimeters, which may limit their ability to measure larger samples or multiple samples at once.
4. Sensitivity to ambient light: Portable/handheld colorimeters may be more sensitive to ambient light than benchtop colorimeters, which can affect the accuracy of their measurements.
5. Short battery life: Some portable/handheld colorimeters may have a shorter battery life than others, which can limit their use in certain applications.
6. Limited customization options: Portable/handheld colorimeters may have fewer customization options than benchtop colorimeters, which may limit their suitability for certain applications.
7. Limited storage capacity: Some portable/handheld colorimeters may have limited storage capacity, which may make it difficult to store and retrieve large amounts of measurement data.

Differences between Benchtop colorimeter and Portable/handheld colorimeter

A benchtop colorimeter is a type of color measurement device that is designed to be used on a laboratory bench or other stationary work surface. A portable or handheld colorimeter, on the other hand, is a smaller, more portable device that can be carried and used in a variety of locations.

Some key differences between benchtop colorimeters and portable/handheld colorimeters include:

1. Size and weight: Benchtop colorimeters are larger and heavier than portable/handheld colorimeters, which makes them less portable and more difficult to carry around.
2. Accuracy: Benchtop colorimeters tend to be more accurate than portable/handheld colorimeters, as they are designed to be used in a controlled laboratory environment.
3. Precision: Benchtop colorimeters are typically more precise than portable/handheld colorimeters, as they use more advanced measurement technologies and have more sophisticated optics.
4. Cost: Benchtop colorimeters are generally more expensive than portable/handheld colorimeters due to their larger size, higher accuracy, and greater precision.
5. Versatility: Portable/handheld colorimeters are generally more versatile than benchtop colorimeters, as they can be used in a variety of locations and can be easily carried from one place to another.

Ultimately, the choice between a benchtop colorimeter and a portable/handheld colorimeter will depend on the specific needs and requirements of the user. If accuracy and precision are the primary concerns, a benchtop colorimeter may be the better choice. However, if portability and versatility are more important, a portable/handheld colorimeter may be a better fit.

Types of Colorimeter Based on filters

1. Tristimulus colorimeters

• This type of colorimeter utilises three filters to measure the intensity of the three primary colors-RGB (red, green, and blue). It is the most prevalent type of colorimeter filter.
• A tristimulus colorimeter is a device used to measure the color of an object or sample by measuring the amount of light it reflects or absorbs in three wavelengths: red, green, and blue. The term “tristimulus” refers to the three wavelengths of light that are used in the measurement.
• Tristimulus colorimeters are commonly used in a variety of applications, including quality control in the manufacturing and printing industries, color matching in the cosmetics and paint industries, and color analysis in the food and beverage industry.
• Tristimulus colorimeters use filters to measure the intensity of light in each of the three wavelengths, and then use a combination of these measurements to determine the color of the sample. The results of the measurement are typically reported as a set of three numerical values, known as the tristimulus values, which represent the amount of light reflected or absorbed in each of the three wavelengths.
• Tristimulus colorimeters are generally more accurate and precise than other types of color measurement devices, and are widely used in industries where color accuracy is critical.

Advantages of Tristimulus colorimeters

Some advantages of using a tristimulus colorimeter include:

1. High accuracy: Tristimulus colorimeters are highly accurate, as they measure the amount of light reflected or absorbed in three wavelengths and use a combination of these measurements to determine the color of the sample.
2. Wide measurement range: Tristimulus colorimeters can measure a wide range of colors, making them suitable for a variety of applications.
3. User-friendly interface: Many tristimulus colorimeters have a user-friendly interface, which makes them easy to use and allows for efficient data collection.
4. Customization options: Tristimulus colorimeters can often be customized with a variety of measurement accessories and options, which allows them to be tailored to specific applications and needs.
5. Low maintenance: Tristimulus colorimeters are generally low maintenance, as they do not require frequent calibration or other maintenance tasks.
6. Long service life: Tristimulus colorimeters have a long service life, provided they are properly maintained and used in accordance with the manufacturer’s instructions.
7. Suitable for a wide range of applications: Tristimulus colorimeters are suitable for use in a wide range of applications, including quality control in manufacturing, color matching in cosmetics and paint, and color analysis in food and beverage.

Disadvantages of Tristimulus colorimeters

Some disadvantages of using a tristimulus colorimeter include:

1. High cost: Tristimulus colorimeters are generally more expensive than other types of color measurement devices due to their advanced measurement technologies and high accuracy.
2. Complex design: Tristimulus colorimeters can be complex in design, which can make them more difficult to operate and maintain.
3. Limited portability: Tristimulus colorimeters are generally less portable than other types of color measurement devices, as they are typically larger and heavier.
4. Limited measurement range: Some tristimulus colorimeters may have a limited measurement range, which may not be suitable for certain applications that require a wider range of measurement.
5. Sensitivity to ambient light: Tristimulus colorimeters may be more sensitive to ambient light than other types of color measurement devices, which can affect the accuracy of their measurements.
6. Limited sample capacity: Tristimulus colorimeters often have a smaller sample capacity than other types of color measurement devices, which may limit their ability to measure larger samples or multiple samples at once.
7. Limited customization options: Some tristimulus colorimeters may have fewer customization options than other types of color measurement devices, which may limit their suitability for certain applications.

2. Densitometer colorimeters

• Densitometer colorimeters have a single filter for measuring the colour intensity of a specific light source. It is used for detecting bacterial and yeast growth density.
• A densitometer colorimeter is a device that measures the density of a sample or substance by measuring the amount of light it absorbs or reflects at a specific wavelength. The term “densitometer” refers to the ability of the device to measure density, while the term “colorimeter” refers to its ability to measure color.
• Densitometer colorimeters are commonly used in a variety of applications, including quality control in the printing and film processing industries, analysis of chemical samples in the laboratory, and measurement of food and beverage products.
• Densitometer colorimeters use filters to measure the intensity of light in a specific wavelength, and then use this measurement to determine the density of the sample. The results of the measurement are typically reported as a numerical value, known as the density value, which represents the amount of light absorbed or reflected by the sample.
• Densitometer colorimeters are generally more accurate and precise than other types of color measurement devices, and are widely used in industries where density accuracy is critical.

Advantages of Densitometer colorimeters

Some advantages of using a densitometer colorimeter include:

1. High accuracy: Densitometer colorimeters are highly accurate, as they measure the amount of light absorbed or reflected at a specific wavelength and use this measurement to determine the density of the sample.
2. Wide measurement range: Densitometer colorimeters can measure a wide range of densities, making them suitable for a variety of applications.
3. User-friendly interface: Many densitometer colorimeters have a user-friendly interface, which makes them easy to use and allows for efficient data collection.
4. Customization options: Densitometer colorimeters can often be customized with a variety of measurement accessories and options, which allows them to be tailored to specific applications and needs.
5. Low maintenance: Densitometer colorimeters are generally low maintenance, as they do not require frequent calibration or other maintenance tasks.
6. Long service life: Densitometer colorimeters have a long service life, provided they are properly maintained and used in accordance with the manufacturer’s instructions.
7. Suitable for a wide range of applications: Densitometer colorimeters are suitable for use in a wide range of applications, including quality control in printing and film processing, analysis of chemical samples in the laboratory, and measurement of food and beverage products.

Disadvantages of Densitometer colorimeters

Some disadvantages of using a densitometer colorimeter include:

1. High cost: Densitometer colorimeters are generally more expensive than other types of color measurement devices due to their advanced measurement technologies and high accuracy.
2. Complex design: Densitometer colorimeters can be complex in design, which can make them more difficult to operate and maintain.
3. Limited portability: Densitometer colorimeters are generally less portable than other types of color measurement devices, as they are typically larger and heavier.
4. Limited measurement range: Some densitometer colorimeters may have a limited measurement range, which may not be suitable for certain applications that require a wider range of measurement.
5. Sensitivity to ambient light: Densitometer colorimeters may be more sensitive to ambient light than other types of color measurement devices, which can affect the accuracy of their measurements.
6. Limited sample capacity: Densitometer colorimeters often have a smaller sample capacity than other types of color measurement devices, which may limit their ability to measure larger samples or multiple samples at once.
7. Limited customization options: Some densitometer colorimeters may have fewer customization options than other types of color measurement devices, which may limit their suitability for certain applications.

3. Spectrophotometer colorimeters

• Spectrophotometer colorimeters use prism to separate white light into its component spectrum colours. It aids in the spectral distribution measurement of light sources.
• A spectrophotometer colorimeter is a device that measures the absorption or reflection of light across a wide range of wavelengths. The term “spectrophotometer” refers to the ability of the device to measure the spectrum of light, while the term “colorimeter” refers to its ability to measure color.
• Spectrophotometer colorimeters are commonly used in a variety of applications, including quality control in the printing, paint, and cosmetics industries, analysis of chemical samples in the laboratory, and measurement of food and beverage products.
• Spectrophotometer colorimeters use a light source and a detector to measure the intensity of light across a wide range of wavelengths. The results of the measurement are typically reported as a spectrum, which is a graph showing the intensity of light at each wavelength.
• Spectrophotometer colorimeters are generally more accurate and precise than other types of color measurement devices, and are widely used in industries where color accuracy is critical.

Advantages of Spectrophotometer colorimeters

Some advantages of using a spectrophotometer colorimeter include:

1. High accuracy: Spectrophotometer colorimeters are highly accurate, as they measure the intensity of light across a wide range of wavelengths and use this information to determine the color of the sample.
2. Wide measurement range: Spectrophotometer colorimeters can measure a wide range of colors and wavelengths, making them suitable for a variety of applications.
3. User-friendly interface: Many spectrophotometer colorimeters have a user-friendly interface, which makes them easy to use and allows for efficient data collection.
4. Customization options: Spectrophotometer colorimeters can often be customized with a variety of measurement accessories and options, which allows them to be tailored to specific applications and needs.
5. Low maintenance: Spectrophotometer colorimeters are generally low maintenance, as they do not require frequent calibration or other maintenance tasks.
6. Long service life: Spectrophotometer colorimeters have a long service life, provided they are properly maintained and used in accordance with the manufacturer’s instructions.
7. Suitable for a wide range of applications: Spectrophotometer colorimeters are suitable for use in a wide range of applications, including quality control in printing, paint, and cosmetics, analysis of chemical samples in the laboratory, and measurement of food and beverage products.

Disadvantages of Spectrophotometer colorimeters

Some disadvantages of using a spectrophotometer colorimeter include:

1. High cost: Spectrophotometer colorimeters are generally more expensive than other types of color measurement devices due to their advanced measurement technologies and high accuracy.
2. Complex design: Spectrophotometer colorimeters can be complex in design, which can make them more difficult to operate and maintain.
3. Limited portability: Spectrophotometer colorimeters are generally less portable than other types of color measurement devices, as they are typically larger and heavier.
4. Sensitivity to ambient light: Spectrophotometer colorimeters may be more sensitive to ambient light than other types of color measurement devices, which can affect the accuracy of their measurements.
5. Limited sample capacity: Spectrophotometer colorimeters often have a smaller sample capacity than other types of color measurement devices, which may limit their ability to measure larger samples or multiple samples at once.
6. Limited customization options: Some spectrophotometer colorimeters may have fewer customization options than other types of color measurement devices, which may limit their suitability for certain applications.
7. Limited measurement range: Some spectrophotometer colorimeters may have a limited measurement range, which may not be suitable for certain applications that require a wider range of measurement.

Differences between Tristimulus colorimeters, Densitometer colorimeters, Spectrophotometer colorimeters

There are several key differences between tristimulus colorimeters, densitometer colorimeters, and spectrophotometer colorimeters:

1. Measurement principle: Tristimulus colorimeters measure the intensity of light in three wavelengths (red, green, and blue) to determine the color of a sample. Densitometer colorimeters measure the intensity of light at a specific wavelength to determine the density of a sample. Spectrophotometer colorimeters measure the intensity of light across a wide range of wavelengths to determine the color and spectral characteristics of a sample.
2. Measurement range: Tristimulus colorimeters can measure a wide range of colors, while densitometer colorimeters are typically limited to measuring density within a narrow range. Spectrophotometer colorimeters can measure a wide range of colors and wavelengths.
3. Accuracy: Tristimulus colorimeters, densitometer colorimeters, and spectrophotometer colorimeters are generally highly accurate, with spectrophotometers being the most accurate due to their ability to measure the intensity of light across a wide range of wavelengths.
4. Cost: Tristimulus colorimeters, densitometer colorimeters, and spectrophotometer colorimeters are generally more expensive than other types of color measurement devices due to their advanced measurement technologies and high accuracy. Spectrophotometers are typically the most expensive due to their wide measurement range and high accuracy.
5. Portability: Tristimulus colorimeters, densitometer colorimeters, and spectrophotometer colorimeters are generally less portable than other types of color measurement devices, as they are typically larger and heavier.
6. Customization options: Tristimulus colorimeters, densitometer colorimeters, and spectrophotometer colorimeters can often be customized with a variety of measurement accessories and options, which allows them to be tailored to specific applications and needs. Spectrophotometers typically have the most customization options.
7. Suitable applications: Tristimulus colorimeters are suitable for use in a wide range of applications, including quality control in manufacturing, color matching in cosmetics and paint, and color analysis in food and beverage. Densitometer colorimeters are suitable for use in applications including quality control in printing and film processing, analysis of chemical samples in the laboratory, and measurement of food and beverage products. Spectrophotometer colorimeters are suitable for use in a wide range of applications, including quality control in printing, paint, and cosmetics, analysis of chemical samples in the laboratory, and measurement of food and beverage products.

Types of Colorimeter Based on the display

1. Analog colorimeter

The display area of an analogue colorimeter is calibrated. The top number scale indicates transmittance, whereas the lower number scale indicates absorbance. Changes in the position of the arrowhead indicate absorbance and transmittance.

Advantages of Analog colorimeter

An analog colorimeter is a type of color measurement device that uses an analog system to measure the color of a sample. Some advantages of using an analog colorimeter include:

1. Simplicity: Analog colorimeters are generally simpler in design than other types of color measurement devices, which can make them easier to operate and maintain.
2. Low cost: Analog colorimeters are generally less expensive than other types of color measurement devices due to their simpler design and fewer advanced measurement technologies.
3. Customization options: Analog colorimeters can often be customized with a variety of measurement accessories and options, which allows them to be tailored to specific applications and needs.
4. Wide measurement range: Analog colorimeters can measure a wide range of colors, making them suitable for a variety of applications.
5. Long service life: Analog colorimeters have a long service life, provided they are properly maintained and used in accordance with the manufacturer’s instructions.
6. Suitable for a wide range of applications: Analog colorimeters are suitable for use in a wide range of applications, including quality control in manufacturing, color matching in cosmetics and paint, and color analysis in food and beverage.

Disadvantages of Analog colorimeter

Some disadvantages of using an analog colorimeter include:

1. Low accuracy: Analog colorimeters are generally less accurate than other types of color measurement devices due to their simple measurement technologies.
2. Limited measurement range: Some analog colorimeters may have a limited measurement range, which may not be suitable for certain applications that require a wider range of measurement.
3. Sensitivity to ambient light: Analog colorimeters may be more sensitive to ambient light than other types of color measurement devices, which can affect the accuracy of their measurements.
4. Limited sample capacity: Analog colorimeters often have a smaller sample capacity than other types of color measurement devices, which may limit their ability to measure larger samples or multiple samples at once.
5. Limited customization options: Some analog colorimeters may have fewer customization options than other types of color measurement devices, which may limit their suitability for certain applications.
6. Complex design: Analog colorimeters can be complex in design, which can make them more difficult to operate and maintain.
7. Limited portability: Analog colorimeters are generally less portable than other types of color measurement devices, as they are typically larger and heavier.

2. Digital colorimeter

The digital colorimeter shows information on an LED screen. Absorbance and transmittance are displayed in decimal format. Analog colorimeters are being rapidly replaced by digital colorimeters.

Advantages of Digital colorimeter

A digital colorimeter is a type of color measurement device that uses a digital system to measure the color of a sample. Some advantages of using a digital colorimeter include:

1. High accuracy: Digital colorimeters are generally more accurate than analog colorimeters due to their advanced measurement technologies.
2. Wide measurement range: Digital colorimeters can measure a wide range of colors, making them suitable for a variety of applications.
3. User-friendly interface: Many digital colorimeters have a user-friendly interface, which makes them easy to use and allows for efficient data collection.
4. Customization options: Digital colorimeters can often be customized with a variety of measurement accessories and options, which allows them to be tailored to specific applications and needs.
5. Low maintenance: Digital colorimeters are generally low maintenance, as they do not require frequent calibration or other maintenance tasks.
6. Long service life: Digital colorimeters have a long service life, provided they are properly maintained and used in accordance with the manufacturer’s instructions.
7. Suitable for a wide range of applications: Digital colorimeters are suitable for use in a wide range of applications, including quality control in manufacturing, color matching in cosmetics and paint, and color analysis in food and beverage.

Disadvantages of Digital colorimeter

Some disadvantages of using a digital colorimeter include:

1. High cost: Digital colorimeters are generally more expensive than analog colorimeters due to their advanced measurement technologies and high accuracy.
2. Limited portability: Digital colorimeters are generally less portable than other types of color measurement devices, as they are typically larger and heavier.
3. Sensitivity to ambient light: Digital colorimeters may be more sensitive to ambient light than other types of color measurement devices, which can affect the accuracy of their measurements.
4. Limited sample capacity: Digital colorimeters often have a smaller sample capacity than other types of color measurement devices, which may limit their ability to measure larger samples or multiple samples at once.
5. Limited customization options: Some digital colorimeters may have fewer customization options than other types of color measurement devices, which may limit their suitability for certain applications.
6. Complex design: Digital colorimeters can be complex in design, which can make them more difficult to operate and maintain.
7. Limited measurement range: Some digital colorimeters may have a limited measurement range, which may not be suitable for certain applications that require a wider range of measurement.

Differences between Analog colorimeter and Digital colorimeter

There are several key differences between analog and digital colorimeters:

1. Measurement principle: Analog colorimeters use an analog system to measure the color of a sample, while digital colorimeters use a digital system.
2. Accuracy: Digital colorimeters are generally more accurate than analog colorimeters due to their advanced measurement technologies.
3. Cost: Digital colorimeters are generally more expensive than analog colorimeters due to their advanced measurement technologies and high accuracy.
4. Customization options: Analog and digital colorimeters can often be customized with a variety of measurement accessories and options, which allows them to be tailored to specific applications and needs. Digital colorimeters typically have more customization options than analog colorimeters.
5. Measurement range: Both analog and digital colorimeters can measure a wide range of colors, but digital colorimeters may have a wider range due to their advanced measurement technologies.
6. Portability: Analog and digital colorimeters are generally less portable than other types of color measurement devices, as they are typically larger and heavier.
7. Suitable applications: Both analog and digital colorimeters are suitable for use in a wide range of applications, including quality control in manufacturing, color matching in cosmetics and paint, and color analysis in food and beverage.

Standard Operating Procedure of Colorimeter

1. Before using a colorimeter, it must be calibrated using standard solutions containing the known concentration of the solute whose concentration must be determined in the test solution. For this, the cuvettes are filled with standard solutions and placed in the colorimeter’s cuvette holder.
2. A beam of light with a specified wavelength for the test is aimed towards the solution. Before reaching the solution, the light ray goes through a variety of filters and lenses. These lenses are utilised for the navigation of coloured light within the colorimeter, while the filter splits the light beam into multiple wavelengths and allows the needed wavelength to pass through to the cuvette containing the standard or test solutions. It analyses the reflected light and compares it to a standard solution that has been established beforehand.
3. When monochromatic light (light of a single wavelength) hits the cuvette, some of the light is reflected, some of the light is absorbed by the solution, and the rest of the light is transmitted through the solution and falls on the photodetector system. The photodetector system monitors the transmitted light intensity and turns it into electrical impulses for transmission to the galvanometer.
4. The galvanometer measures and displays electrical signals in digital format. This computer representation of the electrical signals is the solution’s absorbance or optical density.
5. If the absorption of the solution is high, more light will be absorbed by the solution, whereas if it is low, more light will be transmitted through the solution, which influences the galvanometer reading and correlates to the solute concentration in the solution. One can easily establish the solution’s concentration by plugging all the data into the formula provided in the following section.

Formula to determine substance concentration in test solution.

A = ∈cl

For standard and test solutions

∈ and l are constant

AT = CT ….. (i)

AS = CS ….. (ii)

From the above two equations,

AT × CS = AS × CT

CT = (AT/AS) × CS

Where,

• CT is the test solution concentration
• AT is the absorbance/optical density of test solution
• CS is the standard concentration
• AS is the absorbance / optical density of standard solution

Uses of Colorimeter

• It is also utilised by the culinary and manufacturing industries to produce textiles and paints.
• In laboratories and hospitals, it is utilised to evaluate biochemical samples such as urine, cerebrospinal fluid, plasma, serum, etc.
• It is utilised in the production of paints.
• Utilized in the textile industry.
• It is utilised in the quantification of proteins, glucose, and other biological substances.
• It is used to test the purity of water.
• It is used to determine the haemoglobin concentration in the blood.
• In the medical field, colorimeters are commonly used to measure biochemical samples such as blood, urine, cerebral spinal fluid, plasma, serum, etc.
• They are utilised to analyse the colour contrast and brightness of mobile, computer, and television screens in order to deliver the optimal viewing experience for users.
• In addition, it is utilised in the paint and textile industries.
• It is used to measure the quality of print paper and printing ink in the printing business.
• In addition, they are utilised to evaluate water quality and identify chemical compounds such as chlorine, fluorine, cyanide, iron, molybdenum, etc.
• They are used to determine the quality of diamonds in jewellery.
• A colorimeter is used to measure the haemoglobin concentration in blood samples.
• It aids in the monitoring of soil nutrient concentration for plant growth.
• In the pharmaceutical sector, colorimeters are used to identify defective products and medications.

Disadvantages of Colorimeter

• The colorimeter is quite pricey.
• Some surfaces reflect light, making measuring challenging.
• It is ineffective in UV and IR areas.
• We cannot provide a precise wavelength, as we only establish parameter ranges.
• The method for estimating the concentration of colourless compounds gets increasingly tedious.

Advantages of Colorimeter

• Precise and accurate colour measuring.
• Permits the measuring of a broad spectrum of colours.
• Useful for measuring colours in the visible and invisible spectrums.
• Useful for measuring the hue of both solid and liquid samples.
• Simple to use.
• The result is accessible in less than 1 second.
• With four AA batteries, a portable, pocket-sized colorimeter can take between 100 and 300 readings.
• It is affordable.
• Modifiable and transportable with ease.

Precautions on Using of Colorimeter

1. This gadget is a highly accurate measuring device. During the measurement, it should be avoided that the external environment dramatically alters the instrument. For instance, flashing ambient light should be avoided during measurements.
2. This device is not waterproof and should not be used in environments with high humidity or water spray.
3. Maintain the instrument’s cleanliness and orderliness. Prevent liquids, powders, and solid foreign particles from entering the measuring calibre and equipment. Avoid collision and impact with the instrument.
4. Remove the battery if the instrument will not be used for an extended period of time.
5. If a power adapter other than the one made by our firm is used, the instrument may catch fire.
6. After using the instrument, the colorimeter and whiteboard cover should be carefully stored in the instrument box.
7. To avoid damaging the instrument, it should be stored in a dry, cool atmosphere.

Things To Remember

• Colorimeter is used to measure the intensity of a coloured compound.
• It is operative in the visible range of the electromagnetic spectrum.
• Colorimeter works on the principle of Beer-Lambert’s law.
• It should be calibrated by using a standard solution of known concentration.
• It has a wide variety of applications in the field of medicine, textile, printing, food processing, agriculture, etc.
• They are used in jewellery to measure diamond quality.

Colorimeter vs Spectrophotometer

A spectrophotometer is an equipment that measures the amount of light absorbed at specific wavelengths by a substance. By measuring the absorption of light as it passes through a sample, it is used to examine the composition of a substance. Spectrophotometers are frequently used in pharmaceutical, food, and environmental testing industries for scientific research, chemical analysis, and quality control.

A colorimeter is an instrument for measuring the colours of light that are reflected or transmitted by a sample. It measures the colour intensity of a solution to determine the concentration of a drug in a solution. In industries such as printing, textiles, and cosmetics, colorimeters are routinely used to maintain colour consistency.

Spectrophotometers are typically more sensitive and precise than colorimeters. Additionally, they are more expensive and require additional training. Colorimeters are easier to operate and better suited to applications that do not require high precision.

What Is Colorimeter?

A colorimeter is an instrument that measures how much of a specific colour of light a solution absorbs. Either a set of coloured filters or LED bulbs that emit certain colours of light are included with a colorimeter. Before using a colorimeter, the suitable colour must be chosen. A cuvette containing the solution is then positioned within the colorimeter.

The colorimeter will then provide the absorbance for the chosen colour. It is essential to note that a solution of a given colour absorbs the least amount of its own colour. For instance, a chlorophyll-containing green solution will absorb green colour the least.

What Is Spectrophotometer?

Spectrophotometers measure light’s transmittance and reflectance in relation to its wavelength. In other words, it measures transmittance and reflectance for all colours of light and displays how transmittance/reflectance fluctuates as the colour of light is altered. Unlike a colorimeter, a spectrophotometer can detect wavelengths in the infrared and ultraviolet areas of the electromagnetic spectrum, in addition to the visual range.

The Difference Between Colorimeter and Spectrophotometer

Both colorimeters and spectrophotometers employ a solution and a light beam to measure the absorption of light, but there are significant distinctions between the two instruments. Therefore, let us explain these distinctions.

1. Main Function: The primary function of a colorimeter is to measure the amount of transmitted light absorbed by a specific solution. Nevertheless, a spectrophotometer evaluates the intensity of light as a function of the colour or wavelength of light by measuring the transmittance level.
2. Approach: Colorimeter results in psychophysical analysis, providing colour measurement physiologically similar to how the human eye and brain perceive colour. As a result of spectrophotometer’s physical analysis, colorimetric information can be collected indirectly.
3. Sensitivity: In terms of sensitivity, colorimeters are regarded as less sensitive equipment than spectrophotometers.
4. Cost: The cost of spectrophotometers is more than that of colorimeters.
5. Complexity: The colorimeter is less complex, lighter in weight, and more durable than the spectrophotometer, resulting in less wear and tear during operation. The spectrophotometer, on the other hand, is considerably heavier and hence more complex.
6. Capability: Ability to immediately read colorimetric data and provide tristimulus values such as XYZ, G, b, d, etc. While spectrophotometers are capable of indirectly calculating psychophysical data,
7. Components: Colorimeters consist of a sensor and a straightforward data processor. It has only one combination of illuminant and spectator. Spectrophotometers consist of a sensor, a data processor, and computer software on occasion. In addition, there are numerous available illuminant or observer combinations. In addition, colorimeters contain stationary parts while spectrophotometers have non-stationary parts.
8. Weight: In terms of weight, spectrophotometers are heavier than colorimeters.
9. Wavelength: The visible portion of the electromagnetic spectrum is the only light that the colorimeter can detect. However, spectrophotometers also measure invisible and ultraviolet light in addition to visible light.
10. Functionality: The colorimeter measures the three basic colour components of light to quantify colour. While spectrophotometer determines the precise colour within the wavelength of visible light to the human eye,
11. Operation: Utilizing a tristimulus absorption filter, the colorimeter separates a broad band of wavelengths. In contrast, a spectrophotometer isolates a limited band of wavelengths using an interference filter or grating and prism.
12. Display of Data: Colorimeters display data on a digital or analogue output. In spectrophotometers, data are generated and recorded using software.
13. Usage: The colorimeter is the ideal instrument for quality inspection. It is effective at adjusting minor colour discrepancies under steady conditions and routinely compares similar hues. In addition to quality control, the spectrometer is the optical instrument of choice for research and development. It is effective for measuring metamerism and observer circumstances as well as changeable illumination and colour formulation.
14. Application: On the basis of absorbance, colorimeters can be used to determine the concentration of an individual component. In contrast, spectrophotometers can be used to identify and quantify inorganic and organic biological compounds.

Key Differences Between Colorimeter and Spectrophotometer

• A colorimeter is an equipment that measures the amount of light rays transmitted by a certain solution that are absorbed. The transmittance level of a spectrophotometer measures the intensity of light as a function of its colour or wavelength.
• Psychophysical analysis is the outcome of the colorimeter, which provides colour measurement physically similar to how the human eye and brain perceive colour. As a result of spectrophotometer’s physical analysis, colorimetric information can be collected indirectly.
• In comparison to spectrophotometers, colorimeters are regarded as less sensitive equipment.
• Colorimeters are less expensive than spectrophotometers.
• The design of a colorimeter is simpler, lighter, and more durable than that of a spectrophotometer, resulting in less wear and tear during operation. This is in contrast to the spectrophotometer, which is considerably heavier and more complex.
• Spectrophotometers have non-stationary parts, whereas colorimeters have fixed parts.
• Spectrophotometers offer variable wavelengths in the UV, infrared, and visible spectrum ranges, whereas colorimeters offer fixed wavelengths in the visible spectrum region.
• Colorimetric analysis yields tristimulus data, whereas spectrophotometric analysis yields colorimetric data inferentially.
• Adjustments to colour comparison and colour difference can be made using colorimetric testing. While the spectrophotometer aids in colour formulation and the measurement of varied illumination, it also measures the variable illuminant.
• The colorimeter determines the concentration of the substance based on the intensity of absorption. In contrast, light intensity helps distinguish between organic and inorganic molecules.

Examples of Colorimeter

1. Hach Colorimeter

Hach is a manufacturer and retailer of a variety of water testing tools, including colorimeters. A Hach colorimeter is a portable instrument that detects the concentration of a particular drug in a liquid sample by comparing the sample’s colour to a standard colour. Typically, the chemical to be measured is added to the sample as a reagent, which interacts with the substance to form a coloured solution.

In addition to water treatment and analysis, Hach colorimeters are utilised in a variety of other industries, including food and beverage, agriculture, and environmental testing. They are renowned for their precision, dependability, and user-friendliness. Hach offers a variety of colorimeters with varying features and capabilities for various purposes. Some versions are built for specific compounds, like as chlorine or ammonia, but others are more adaptable and can be used with a variety of substances.

Advantages of Using Hach colorimeter

Using a Hach colorimeter for water testing and analysis has various benefits:

• Accuracy: Hach colorimeters are renowned for their accuracy, with a typical measurement error of less than 1%. This means that you can rely on the results of your tests and base choices on them with confidence.
• Ease of use: Hach colorimeters are meant to be user-friendly, even for those with minimal or no scientific expertise. They have calibration instructions and are simple to calibrate.
• Portability: The portability of Hach colorimeters makes them suitable for usage in the field or in isolated areas.
• Wide range of applications: Hach offers a vast selection of colorimeters for a variety of applications, including water treatment, agricultural, and environmental testing. This allows you to select a model that is tailored to your requirements.
• Versatility: Numerous Hach colorimeters are adaptable and capable of measuring a vast array of chemicals. This allows you to save time and money by using the same instrument for numerous testing applications.
• Support: Hach offers complete training and support for its colorimeters, including online materials, technical assistance, and customer care.

2. Hunter lab colorimeter

HunterLab is a manufacturer and distributor of a variety of colour measurement tools, including colorimeters. A HunterLab colorimeter is a device that measures the colours of light reflected or transmitted by a sample and estimates the concentration of a given drug depending on the color’s intensity.

HunterLab colorimeters are utilised in a range of industries, such as printing, textiles, and cosmetics, to assure colour consistency. In industries such as the pharmaceutical, food and beverage, and environmental testing, they are also utilised for research and quality control.

HunterLab offers a variety of colorimeters with varying features and capabilities for various purposes. Some versions are built for specific compounds, like as chlorine or ammonia, but others are more adaptable and can be used with a variety of substances. HunterLab colorimeters are renowned for their precision, dependability, and user-friendliness. In addition to being portable and simple to calibrate, they are suitable for usage in the field or in remote areas.

3. Xrite colorimeter

X-Rite is a manufacturer and distributor of a variety of colour measurement tools, including colorimeters. A X-Rite colorimeter analyses the colours of light reflected or transmitted by a sample and determines the concentration of a specific drug in the sample depending on the color’s intensity.

To assure consistent colour quality, X-Rite colorimeters are widely utilised in numerous industries, including printing, textiles, and cosmetics. In industries such as the pharmaceutical, food and beverage, and environmental testing, they are also utilised for research and quality control.

X-Rite offers a variety of colorimeters with varying features and capabilities for various purposes. Some versions are built for specific compounds, like as chlorine or ammonia, but others are more adaptable and can be used with a variety of substances. X-Rite colorimeters are renowned for their precision, dependability, and user-friendliness. In addition to being portable and simple to calibrate, they are suitable for usage in the field or in remote areas.

4. Vernier colorimeter

A Vernier colorimeter is an instrument that measures the colours of light reflected or transmitted by a sample and estimates the concentration of a specific drug in the sample depending on the color’s intensity. Vernier is a manufacturer and retailer of a variety of scientific instruments, including colorimeters.

To assure consistent colour quality, Vernier colorimeters are utilised in a range of industries, including printing, textiles, and cosmetics. In industries such as the pharmaceutical, food and beverage, and environmental testing, they are also utilised for research and quality control.

Vernier offers a variety of colorimeters with varying features and capabilities for various purposes. Some versions are built for specific compounds, like as chlorine or ammonia, but others are more adaptable and can be used with a variety of substances. Vernier colorimeters are renowned for their precision, dependability, and user-friendliness. In addition to being portable and simple to calibrate, they are suitable for usage in the field or in remote areas.

5. Handheld colorimeter

A handheld colorimeter is a portable device that measures the colors of light reflected or transmitted by a sample and calculates the concentration of a specific substance in the sample based on the intensity of the color. Handheld colorimeters are designed to be easy to use and convenient for field or on-site testing, and they are often used as an alternative to more complex and expensive instruments such as spectrophotometers.

Handheld colorimeters are widely used in a variety of industries, including water treatment, agriculture, and environmental testing, as well as in research and quality control. They are known for their accuracy, reliability, and ease of use, and they are often used to test for substances such as chlorine, pH, and dissolved oxygen.

To use a handheld colorimeter, the user adds a reagent to the sample that reacts with the substance to be measured. The reaction produces a colored solution, and the colorimeter measures the intensity of the color. The concentration of the substance in the sample can then be calculated based on the intensity of the color and the known properties of the reagent. Handheld colorimeters may have filters to select specific wavelengths of light, and they may also have memory capabilities for storing and recalling test results.

6. Pocket colorimeter ii

The Pocket Colorimeter II is a portable, handheld device made by Hach that is used to measure the concentration of a specific substance in a liquid sample. It works by comparing the color of the sample to a reference color and determining the concentration of the substance based on the intensity of the color.

To use the Pocket Colorimeter II, the user adds a reagent to the sample that reacts with the substance to be measured. The reaction produces a colored solution, and the Pocket Colorimeter II measures the intensity of the color. The concentration of the substance in the sample can then be calculated based on the intensity of the color and the known properties of the reagent.

The Pocket Colorimeter II is widely used in a variety of industries, including water treatment, agriculture, and environmental testing, as well as in research and quality control. It is known for its accuracy, reliability, and ease of use, and it is often used to test for substances such as chlorine, pH, and dissolved oxygen. It is powered by batteries and is portable, making it convenient for use in the field or in remote locations.

FAQ

References

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