How would you characterize the flame test with respect to its sensitivity

Flame test is the procedure to find out the metal ions in the ionic compounds. By observing the color of flame we find out the presence of certain metallic ion. For example if we take the test of copper halide, the flame will become of the bluish green color due to the copper ion. You can perform the test with the common salt. Upon putting it on the flame, the color of flame will become yellow due to the presence of sodium ion. Similarly aluminium shows blue and calcium brick red etc.