Merits and Limitations of Flame Photometry:

You have learnt in which flame photometry is appropriate for qualitative and quantitative determination of various cations, especially for metals which are simply excited to higher energy stages at a relatively low flame temperature. The metals majorly are Na, Rb, Cs, K, Ca, Ba and Cu. The salient features of analysis through flame photometry could be summarized as follows.

• Propane-air or natural gas-air mixtures which provide good flame along with strong heat and minimal background light emission are used for the atomisation.
• The solvent blank is run for setting zero emission.
• Since the concentration intensity relationship is not valid for all concentrations, the solutions are suitably diluted to fall inside linear part of the calibration curve.
• The use of solutions of extremely low concentration of Na⁺ and K⁺ solutions are avoided as these may encounter problems of contamination; especially within case of Na⁺ that leaches slowly from glass and on contact along with skin.
• Interference effects of anions and cations could cause errors and required to be suitably accounted for.
• Here the random flame instability and random dilution errors could be minimised through using an internal standard (lithium).