Limitations:

The flame photometric methods such as several other techniques have a few limitations also. These are given below.

• Since natural gas and air flame is employed for excitation the temperature is not high sufficient to excite transition metals, thus the method are selective towards detection of alkali and alkaline earth metals.
• The low temperature renders this technique susceptible to certain drawbacks, most of them associated to interference and the stability of the flame and aspiration conditions. Oxidant and Fuel flow rates and aspiration rates, purity, solution viscosity, affect these. It is thus extremely significant to measure the emission of the standard and unknown solutions under identical conditions.
• The associatively low energy available from the flame leads to relatively low intensity of the radiation from the metal atoms, particularly those which need large amount of energy to become excited.
• Flame photometry is a means of determining the total metal concentration of a sample; it tells us nothing about the molecular create of the metal within the original sample.
• Only liquid samples could be used. Within some cases, lengthy steps are essential to prepare liquid samples.

Despite the limitations, a flame photometry is extensively used because of its portability, ease of operation, etc.