Principle and Procedure of Flame Photometer

A flame photometer is a device used in inorganic chemical analysis for the determination of certain metal ions such as potassium, sodium, calcium and lithium. Photoelectric flame photometry is based on determining the intensity of emitted light produced when a metal is introduced into a flame.


  1. What is the flame photometer?
  2. Principle of operation of the flame photometer
  3. Flame photometer procedure
  4. Applications of the flame photometer
  5. Advantages of the flame photometer
  6. Disadvantages of the flame photometer
  7. Difference Between Spectrophotometer and Flame Photometer
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Principle of operation of the flame photometer:

The principle of operation of the flame photometer is simple. The liquid is sprayed with a non-shiny flame in the form of a fine colored mist depending on the characteristic emissions of the elements, for example, sodium (Na), potassium (K), calcium (Ca) and lithium ( Li). . The flame is detected by a photodetector which observes the flame through a very narrow band optical filter which only lets through the wavelength (nm) according to the characteristic emission of the chosen element.

The output of the photodetector is fed into electronic modules which provide digital readings of the desired element concentration. The method must be calibrated with known concentrations of the solution, before testing the unknown liquid sample.

Compressed air is supplied to an atomizer in a metering system using a compressor, resulting in an airflow at the end of an atomizer, which draws sample fluid from the mixing chamber and in the mixing mixing chamber. Liquid Petroleum Gas (LPG) is also used at controlled pressure in the mixing chamber; here the atomized sample and gas are delivered to the burner and ignited.

Light from the flame is emitted by the optical lenses and transmitted to the flame photometer detector through a selected filter. Electronically analyzed detector data and sample solution results are displayed correctly.

Flame photometer procedure:

Before starting a flame photometry workflow, one must recognize the various components that are essential to successfully complete the process. The flame photometer consists of four main components, such as flame source, nebulizer and mixing chamber, optical filter and photodetector.

1. Source of flame: A burner delivers the flame and can be kept stable and at a constant temperature.

2. Nebulizer and mixing chamber: This helps to move the sample solution from molecules to a flame at a constant speed.

3. Optical filter (optical system): The optical system consists of three elements such as the lens, the filter and the convex mirror. This separates the wavelength from any other extraneous emission to be measured.

4. Photodetector: Detect the light emitted and determine the level of radiation produced by the flame.

Flame Photometer Operation Procedure:

  • Prepare standard solutions and samples as needed
  • Make sure the air, gas and drain hose connection is correct.
  • Turn on the flame photometer and compressor according to the instruction manual
  • Adjust the outlet pressure and soak the capillary tube in distilled water.
  • Turn on the gas supply and immediately ignite the flame.
  • Fill the blank with the diluent used for the preparation of standards and samples.
  • Aspirate standard samples sequentially.
  • Aspirate the sample solution and record the readings.
  • Go through the device shutdown process.

Flame photometer applications:

  • The flame photometer determines the concentration of potassium (K), sodium (Na) and calcium (Ca) ions which are extremely important for the activity of various metabolic functions in the human body.
  • It is used for the qualitative and quantitative study of its components.
  • The amount of different alkali and alkaline earth metals in the soil can be determined using a flame test.
  • It can be used for the determination of calcium in milk, beverages, beer and other products.
  • Flame photometry is used to determine the concentration of various elements and metals present in fruit juices, alcoholic beverages and carbonated drinks.
  • Flame photometry is used in pharmaceutical analysis.

Advantages of the flame photometer:

  • Flame photometry is an accurate, fast and sensitive technique.
  • It is a cost-effective technique compared to others.
  • Qualitative and quantitative analysis of metal ions is possible using flame photometry.
  • It does not require a specialist to handle it, as it is easy to use
  • Very low concentrations (PPM/PPB) of metal ions can be determined with this method.

Disadvantages of flame photometer:

  • The main disadvantage of flame photometry is that it only analyzes the liquid sample.
  • This technique does not provide details of the molecular structure of the metal ion.
  • This often requires calibration, in some cases more time is needed to prepare the sample.
  • The metal ion concentration cannot be accurately measured by this method.
  • Flame photometry cannot analyze every metal atom.

Difference between a spectrophotometer and a flame photometer:

The main difference between spectrophotometer and flame photometer is that spectrophotometer uses the absorption of light by molecules in a sample whereas flame photometry uses a controlled flame test.

Frequently asked Questions:

What is a flame photometer?

It is a spectrophotometer in which a mist of metallic salts in solution is vaporized in a very hot flame and evaluated quantitatively by calculating the strength of the metallic spectral lines.

What is the basic principle of the flame photometer?

The principle of flame photometry is based on determining the intensity of the light emitted when a metal ion is introduced into a flame.

What type of spectroscopy is flame photometry?

It is a type of atomic spectroscopy which is used to determine the concentration of certain metal ions, for example calcium, sodium, potassium, lithium, etc.

What is the main advantage of flame photometry?

Its main advantage is the analysis of alkali and alkaline earth metals by flame photometry.

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