Flame Photometry in Analytical Pharmacology

Definition & overview

• Definition — Flame photometry (flame emission photometry / flame emission spectroscopy) is an analytical technique in which a sample solution is introduced into a flame whose heat excites the atoms of certain metallic elements; on returning to the ground state these atoms emit light of a characteristic wavelength, and the intensity of the emitted light is directly proportional to the concentration of the element in the sample.
• Emission family — it belongs to the emission spectroscopic methods — the flame is the excitation source, and works because the relatively low energy of an ordinary flame suffices to excite a few elements, mainly the alkali metals; it is fundamentally an atomic-emission technique, not a molecular one.
• Lab role — in the pharmacology laboratory it is the routine method for estimating Na⁺ and K⁺ in urine and serum, and is the assay of choice for the electrolyte readout in renal/diuretic experiments (e.g. estimating urinary Na⁺/K⁺ after frusemide).