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  • The BWB Team

Flame Photometer Function: How does it work and why do we use it?

What Is Its Function?

The flame photometer is a highly regarded scientific instrument used for measuring the presence and concentration of metal ions, particularly the alkali and alkaline earth metals, in a solution. This is determined through the science of flame emission spectroscopy. The target metals are Barium, Calcium, Lithium, Potassium, and Sodium.

How Does It Work?

Fundamentally, it comes down to five operations to achieve a measurement. Let’s briefly look at each one.

1 - Preparation of samples: By its very nature, flame photometry tests samples in solution form. Most fluids lend themselves to this sort of testing but that doesn’t preclude testing solids. Solids, even biological solids, can be ashed in a furnace, centrifuged, added to distilled water, and filtered to remove extraneous solids while releasing the metal components sought for measurement.

Knowing the original mass and its ultimate dilution allows the investigator to precisely determine the original Parts Per Million (ppm) of the sample. Concentration and dilution are extremely important factors in FP analysis since flame photometry has ranges over which it is most accurate.

2 - Atomisation: Once in liquid form, the sample can be introduced to the flame. Stable flames and extreme quality burners and gas mixers are essential for precision. Gas selections can vary from hydrogen or acetylene and air mixture to a more conventional Propane or Liquefied Petroleum Gas (LPG) with air. The sample is drawn through a small diameter tube when faster moving gas passes over the tip, causing the liquid to atomise and become suspended.

This mixture can be introduced to the flame where the carrier (water) instantly evaporates, leaving just the metal ions behind. Those ions are excited by the heat and begin to radiate as their valance electrons shift from low to high energy states and back again to low.

3 - Light Emission: Now we can see the unique colour(s) of light for the metal(s) present. For example, sodium will present with a yellow flame, whereas potassium will show purple. Of course, the full spectrum isn’t terribly useful. We need to look at extremely small parts of its spectrum after the light is passed through a prism so we can see the identifying pattern.

As you can see in the accompanying image, each metal has an utterly distinct set of bands that are different from all the others. It’s just a matter of selecting the strongest band for each one so it cannot be mistaken for another metal. In this way, BWB Photometers are capable of identifying the presence of all five metals at the same time, something that no others can do.

4 - Detection: Through the use of photomultipliers, diffraction grids, and photodetectors we can unerringly detect and identify our materials of interest. The intensity not only identifies the metals present but leads us to our next step…

5 - Quantification: The machine now directly compares the intensities of the selected bands with the calibration curves established initially. This reveals the concentration of the materials in the original sample.

Flame Photometry is a rapid technique for determining the concentration of these metals in various samples. This makes it broadly useful in clinical laboratories analytical chemistry, and environmental monitoring, so let’s look at that more closely.

Why Use Flame Photometry?

Water Treatment

Flame photometry is used in water and waste treatment plants to monitor these metals in water pathways. Controlling these levels protects water treatment processes, prevents systemic issues like scaling, and keeps the public and environment safe.

Clinical Chemistry

Clinical laboratories measure the levels of essential elements like sodium, potassium, and calcium in biological liquids such as blood, cerebrospinal fluid, and urine. Many forms of diagnostic medicine rely on these tests for cures, or for monitoring of chronic medical conditions, such as dialysis for renal problems.

Environmental Monitoring

Environmental analysis helps to determine the concentration of metals in water, soil, and even air samples with the proper collection methods. Monitoring the levels of these metals is critical for evaluating environmental contaminations and safeguarding compliance with regulatory statutes.

Soil and Agricultural Analysis

This BWB instrument is used in soil and agricultural research to measure the concentration of essential nutrients like potassium and calcium in soil samples. Information can help farmers reduce fertiliser over-use, reduce needless runoff, and improve crop yield.

Such a machine can run from electrical power provided by a vehicle, and portable fuel like propane or LPG. This means much more sensitive results, in situ, because hills, dales, proximity to water, and more, all affect levels in the soil.

Quality Control for Industry

In the food and beverage industry FP analyses elemental composition of food products. Determining the levels of sodium and potassium, for example, in various food items, contributes to quality control, compliance with regulatory requirements, and accuracy in labelling. Similarly, in the pharmaceutical industry, it is used to ensure the correct concentration of specific elements in drug formulations.

Research and Development

Researchers use FP to analyse metals in a wide range of samples, contributing to advancements in fields such as chemistry, biochemistry, and materials science. Ultimately, flame photometry provides a rapid and accurate method for quantifying the concentration of specific metal ions. This makes it an extremely versatile tool in many variegated scientific and industrial applications.

Cost Effective

Instrument Cost

The initial cost of acquiring a flame photometer can be a significant factor since prices can range from a single paycheque to the cost of a small car! High-quality, advanced instruments with additional features may come with a much higher price tag, however, there are plenty of models that are more affordable, making the technology accessible for a range of budgets.

Maintenance and Calibration

Analytical instruments require calibration and regular maintenance to ensure accuracy. While this may involve the cost of purchasing (or making) calibration standards and occasional replacement of consumables (such as burner heads or nebulisers) this is a surprisingly affordable instrument with low associated costs.

Training and Personnel

Training personnel to operate and maintain the flame photometer correctly is fast, easy, and such people can be running tests effectively in less than a day! Becoming a skilled operator is essential for obtaining accurate and reproducible results, but the learning curve is quite mild.

Applications and Throughput

Higher throughput lowers the cost due to time-saving efficiencies. Even without automation, it is better to keep the machine busy and running rather than go through daily set-ups. Any process can be paused to check calibration, through drift in the readings are almost negligible.

Fast, Fast, Fast!

Flame photometry is a fast analytical technique compared to other methods that cover the same territory. FP provides a high sample throughput per unit of time, particularly when analysing a large number of samples with similar compositions.

Multi-Channel machines can give results for any single substance, of course, but can report on all five of the easily measurable substances simultaneously, making them up to 400% faster than a single channel machine. Compared to Spectrophotometers the setup time is small, the tests are completed at light-speed, and the costs are trifling. The difference in cost between the technologies is orders of magnitude less for the hardy Flame Photometer!

Modern FP instruments have automated setup algorithms that make first operation fast and easy to obtain, unlike their analogue predecessors. This also eliminates human errors from the setup process.

The sheer speed of flame photometry makes it particularly suitable for routine and high-throughput analyses in various fields, such as environmental monitoring and clinical chemistry.

The Takeaway

There are alternative technologies that can do what a flame photometer does, but they are costly and over-powered for the tasks that most flame photometers users need. If your uses are those described here, don’t over-invest in those other technologies.

Give us a call and let us show you why Flame Photometry is an excellent choice for your laboratory. We would love to hear from you and help you make an economical decision to super-power your lab or process today!


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