Atomic absorption versus flame emission

Current values of the different parameters of expressions 13.1 and 13.2 are shown in Table 13.1 for some elements. Examination of the data reveals that practically all of the atoms remain in their ground state when the energy difference AE is large and the temperature is low. 

Therefore it would seem to be preferable, in all circumstances, to base the measurements upon atomic absorption instead of flame emission, as the absorption spectra are simpler than those of emission. However, the matrix in which the 

with the most modern detectors containing a photomultiplier, reliable measurements can be obtained as long as the ratio N /Nq is greater than 10 . The experience reveals that flame emission is in fact preferable only for five or six elements. This is why the alkaline earths, elements giving coloured flames, are easily measured by emission (Table 13.1). 

CHAPTER 13 - ATOMIC ABSORPTION AND FLAME EMISSION SPECTROSCOPY 

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Procedure Concomitantly determine the absorbance values of the Test Solutions at the potassium emission line at 766.7 nm with a suitable atomic absorption spectrophotometer equipped with an air-acetylene flame, using water as the blank. Plot the absorbance values of the Test Solutions versus their contents of potassium, in micrograms per milliliter draw the straight line best fitting the three points and extrapolate the line until it intersects with the concentration axis. From the intercept, determine the amount, in micrograms, of potassium in each milliliter of Test Solution A. Calculate the percent potassium in the portion of sample taken by multiplying the concentration, in micrograms per milliliter, of potassium found in Test Solution A by 0.2. 

Procedure Concomitantly determine the absorbance values of the Test Solutions at the sodium emission line at 589.0 nm with a suitable atomic absorption spectrophotometer equipped with an air-acetylene flame, using water as the blank. Plot the absorbance values of the Test Solutions versus... 

Procedure Use a suitable atomic absorption spectrophotometer equipped with a sodium hollow-cathode lamp and an oxidizing air-acetylene flame. After using the Blank Solution to zero the instrument, concomitantly determine the absorbances of the Standard Solutions and the Test Solution at the sodium emission line of 589 nm. Plot the absorbances of the Standard Solutions versus concentration, in micrograms per milliliter, of sodium, and draw the straight line that best fits the plotted points. From the graph so obtained, determine the concentration, C, in micrograms per milliliter, of sodium in the Test Solution. Calculate the percentage of sodium in the portion of potassium lactate taken by the formula... 

FIGURE 9-16. Concentration of manganese in g/ml versus peak height in mm. [From W. G. Schrenk, in Flame Emission and Atomic Absorption Spectroscopy, Vol. 2, Edited by J. A. Dean and T. C. Rains, Marcel Dekker, New York (1971), Chapter 12. Used by permission of Marcel Dekker Inc.]... 

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