Why We Use Flame Photometers
Ease, Speed, Cost, and Reliability
Famed in laboratories around the world, the Bunsen Burner was created as more than just a clean, smokeless way to heat glassware and power chemical experiments. Robert Bunsen and Peter Desaga discovered that pure substances each had a unique spectroscopic signature when the resulting light from heating was passed through a prism. This is what would lead them to their discovery of two new elements, named cesium and rubidium in 1860 and 1861, respectively. Such spectra could be rendered either as absorption or emission images. The absorption spectra can be slightly more accurate since the absorption band is fixed based on the electron configuration of the atom itself. The emission band is dependent on the material absorbing the energy, and then re-emitting it by fluorescence, so if the flame is not entirely stable the emissions can be somewhat wider.
Essentially, many find it is easier to see the black lines of missing radiation to make the identification than the brighter lines against a fainter background of color. Both provide largely the same information, and the output is dependent on equipment, preference, or individual needs. In either case they provide an irrefutable fingerprint to identify a specific substance, if it is present.
Unfortunately, detecting most substances requires much more sophisticated equipment, namely Gas Chromatographs or full-fledged Mass Spectrometers. Indeed, even these are giving way to Inductively Coupled Plasma Mass Spectrometry (ICP-MS). They all represent very large investments in equipment, training, expendables, and most importantly, time.
These techniques allow us to detect down to the nmol/l level of accuracy for aluminum, antimony, arsenic, barium, bismuth, bromide, cadmium, chloride, chromium, cobalt, copper, gold, iodine, lead, manganese, mercury, molybdenum, nickel, selenium, silver, thallium, tin, vanadium, and zinc.
Fortunately, in medicine, biotechnology, pharmacologic development, food production, water treatment, and many other fields, there is a method for detecting five inorganic substances from Group I or Group II alkali metals. This faster, more efficient technique is called Flame Emission Spectroscopy (FES) or simply Flame Photometry. It possesses a much narrower capability for detection, but fortunately it is a surprisingly useful range.
To anyone familiar with the technique, these five metals, Barium, Calcium, Lithium, Potassium, and Sodium present easily identifiable spectral lines. Detecting their presence, and determining the quantity through light intensity, can speed medical diagnosis, identify insufficiently treated wastewater, or contribute to industrial processes in innumerable ways.
The biggest advantage of FES is that it can be done by hand (e.g. assaying body fluids), or can be incorporated into an ongoing automated process (processing of food, water management/treatment, etc.) providing near instant or continuous results at a remarkably low cost.
The disadvantage is that the heat of a flame is not sufficient to loosen the electrons responsible for generating the color of the flames in every metal. For example, Magnesium binds its electrons much more tightly and therefore won’t produce a colored flame by this method.
While more information is never a bad thing, when there is a cost attached, only the information you need is worth paying for. Flame Photometers are the perfect intermediate answer for many vital questions. They offer unsurpassed Ease, Speed, Cost Efficiency, and Reliability, and all within a dramatically shortened timeframe.
Or more succinctly: a delivery person shouldn’t invest in a Lamborghini Countach when an e-bike will suffice!