Sensitivity and detection limits in AAS

The detection limit corresponds to the concentration of the element giving a signal whose intensity is equal three times the standard deviation of a series of measurements made upon the analytical blank or on a very dilute solution (degree of confidence 95 per cent). In practice, the concentrations must be at least ten times higher than the detection limit to give reliable measurements. 

1 If the response of the detector of a flame photometer is proportional to the concentration of the element heated to a state of excitation, by what factor is the signal multiplied when the temperature passes from 2000 K to 

2 Why is it advisable to add ethylenediaminetetracetic acid (EDTA) to measure calcium when it is in the form of a phosphate  

3 Why is a potassium salt (such as KCl) frequently added when one wants to measure elemental sodium by flame photometer Remember that the potential for the first ionisation of potassium is 419KJ mol while that for sodium is 496KJmoP  

CHAPTER 13 - ATOMIC ABSORPTION AND FLAME EMISSION SPECTROSCOPY 

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