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  • The BWB Team

Flame Photometer Functions: What do Flame Photometers do?



Just about every student that ever sat in a chemistry class where they conducted practical experiments has had occasion to put a lump of metal in a Bunsen Burner flame and generate a colour.  This manual method can allow them to identify the metal by the colour of the flame it generates in comparison to a chart of known colours for heated metals.  It’s simple and revelatory for the student.

This “Wow!” or “Neat!” moment gives teachers a chance to explain that certain types of metals, when exposed to sufficient heat will colour the flame because ions are escaping the metal in a gaseous form.  This allows the valance electrons to jump up an energy level to an unstable state, but since that is not a tenable position for them, they shed a photon to get back to ground state.


These photons are at very specific wavelengths for each element.  The colours and specific frequencies of light can inform us about the material we’re examining, but it is very crude information.  Comparing two metals with similar colours can lead to misidentification, and alloys can generate nearly unidentifiable mixes of colour when using this manual method.

AES, or Atomic Emission Spectroscopy, often known simply as Flame Photometry, overcomes these difficulties and gives us much more precise information about a substance by using a spectroscope.  This setup is specifically useful for non-organic alkali metals and alkali-earth metals, such as sodium, potassium, beryllium, lithium, and calcium.

By detecting the specific line spectrum that identifies your test substance, you can not only see that it is present, but by measuring the intensity of the light, also see “how much” is there.  You can capture both qualitative and quantitative data simultaneously.

With modern Flame Photometry equipment like our own, you can read all of the measureable metals at the same time.  You don’t need to repeat the test up to five times per sample, thus making the process much more efficient. The first two metals shown here are both present in the readout show below in the third band.  The whole process is simple, fast, and far less expensive to get the results needed than more complex techniques.


The Takeaway


Instrumental measurements surpass manual methods by providing fast results, more accurate results, and more sensitive results.  By that we mean you can measure down to parts per million rather than “yes” or “no”.  Further, with automation, techniques don’t have to rely on a human that may not have gotten enough sleep last night, or just got home from a party, so your results can be very consistent for high volumes of testing on large batches.

Humans are great, and we’ll probably always need them, but any time you can relieve tedium and use human brains for something creative that a machine cannot do is a great day!  It may be bioassays for medical research purposes that need a human present to make judgement calls, or continuous water sampling at a sewage treatment plant.  Bother are essential functions and Flame Photometry is almost always the fastest way to a useful result!

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